The fliers, dropped over parts of the city by Israeli warplanes and posted on social media, did not directly call on people to leave their homes and shelters, but laid out four “safe corridors” for them to flee south to central Gaza “quickly and without inspection.”

“Gaza City will remain a dangerous combat zone,” the fliers warned.

But few appeared to be heeding the warning. In interviews, people in the city said they had decided to stay in their homes or in places where they have been sheltering — including relatives’ homes, hospitals and schools — fearing the potential dangers from Israeli forces on the evacuation routes, and knowing there is no safety in the south.

The United Nations has said repeatedly that the Israeli offensive in Gaza has left nowhere safe. Palestinians there have been forced to flee multiple times amid shifting orders and flare-ups in fighting.

“People have been steadfast now for nearly 270 days, and they won’t be displaced,” even if Israel occupies all of Gaza, Mr. Sidu said. “In my family we agreed that no one will be displaced, and this is how families are in Gaza, despite the lack of water, food and all life’s necessities.”

“The fact is people are being killed wherever we are, either in the north or in the south,” he added.

The United Nations estimates that there are now some 300,000 people in northern Gaza, which includes Gaza City. Since last month, Israeli forces have launched offensives on several parts of the city, saying they were returning to fight remnants of Hamas and other armed Palestinian groups. Israeli forces have been going back to parts of Gaza that they had previously left, especially in the north, which they invaded in October, as Hamas regroups. Their return has sparked new exoduses from those areas.

“People are on the run everywhere,” said Juliette Touma, a spokeswoman for UNRWA, the United Nations agency that helps Palestinians. “It’s probably one of the toughest decisions in life that one can make to leave everything behind.”

Israel first ordered hundreds of thousands of Gazans in the northern part of the territory to flee south in mid-October, a week after the Hamas-led attack on Israel.

Naheel Mehanna, a 41-year-old writer from Gaza City, saw the new leaflets on social media but not in her neighborhood. The Israeli military also calls people multiple times a day with a recorded message warning them to flee south, she said.

“I know this is a message of fear; they want to terrify us to leave,” Ms. Mehanna said. “This is why they continue to call people over the phone, because no one is listening to them, no one is leaving.”

Ms. Mehanna said her friends who fled to the south earlier in the war continue to warn her against leaving Gaza City. “They say it is not safe there at all,” she said.

Gazans also don’t trust assurances by the Israeli military that the evacuation routes are safe. Israeli forces have detained thousands of Gazans, including men of all ages, women and children. Many were stopped as they fled their neighborhoods with their families after the military ordered them to leave.

“There is no opportunity for people to flee south,” said Amani Zanin, 30, who is staying with her parents and numerous aunts and uncles in Gaza City. “The road is not safe.”

The extended family has already been displaced multiple times in northern Gaza and is now sheltering in a school building.

The trip south has to be made on foot, as the Israeli military doesn’t allow vehicles on part of the route. That could take up to four hours, and all that walking in the summer heat would be too much for some of her older relatives.

“It is difficult for us to go south,” Ms. Zanin said. “We heard about leaving, but we haven’t seen anyone who has left.”

Abu Bakr Bashir and Ameera Harouda contributed reporting.

Israeli forces and Hezbollah fighters in Lebanon, who are backed by Iran, have traded fire since the war in Gaza began after Hamas led an attack on Israel on Oct. 7. About 150,000 people in northern Israel and southern Lebanon have fled their homes because of the fighting, and world leaders are worried that continued hostilities could quickly spiral into a full-fledged war that further destabilizes the already fraught region.

Mr. Nasrallah, in his speech, referred to these concerns, noting that “many delegations” from the international community have visited Lebanon to discuss defusing tensions. “We repeated the same words: If you want to stop the northern front, stop the fire in Gaza,” he said.

But the cease-fire talks have been halting, and the fighting between Israel and Hezbollah — cross-border attacks with drones, rockets and airstrikes — has escalated in recent weeks, heightening fears that a wider war may be imminent.

On Tuesday, two Israelis — Noa and Nir Baranes, a married couple from Kibbutz Ortal in the northern Golan Heights — were killed in a Hezbollah strike on their car that the Lebanese armed group said had targeted an Israeli military base in response to an earlier Israeli “assassination” of a Hezbollah figure in Syria. The civilian deaths put additional pressure on the Israeli government to address tensions with Hezbollah, even as the Israeli military keeps returning to parts of Gaza it had previously considered pacified to suppress a resurgence of Hamas fighters.

The Israeli military said on Wednesday that its air force struck a “military site” in southern Lebanon after soldiers identified several Hezbollah operatives entering it, and that it also had targeted other Hezbollah sites nearby. Israeli government officials and military leaders have in recent weeks toured northern Israel and met with troops stationed there who were preparing for a potential escalation.

Israel has invaded Lebanon three times in the last 50 years, most recently in 2006, when the sides fought a monthlong war that killed more than 1,000 people in Lebanon, mostly civilians, and more than 150 in Israel, mostly soldiers.

Yoav Gallant, Israel’s defense minister, has said that a diplomatic solution to the conflict with Hezbollah is preferable. But he has also emphasized, including in talks with his U.S. counterpart, Lloyd J. Austin III, in Washington late last month, that Israel is “determined to establish security” in the north and change “the reality on the ground.”

Israeli security experts are concerned that a war against Hezbollah will be more intense — and more likely to draw in other players — than the fight against Hamas.

A new report from Tel Aviv University’s Institute for National Security Studies warned that “Hezbollah has the military capabilities to conduct an exceedingly protracted war, probably lasting many months, and cause severe damage to Israel” and that it could turn into “a multi-front war against Iran and its other proxies.”

The report, led by the retired Israeli Brig. Gen. Meir Elran, a senior researcher at the institute, said “there is a growing sense of futility regarding the future of the northern border.” It also noted that “public discourse has been heavily focused on the possibility of a comprehensive war with Hezbollah.”

Comprehensive war is precisely what France, the United States and others have been hoping to prevent with diplomatic visits to the region. Whether efforts at de-escalating the conflict between Israel and Hezbollah can succeed may well depend on how the cease-fire talks in Qatar progress.

On Wednesday, the C.I.A. director, Mossad chief and Egyptian intelligence head met in Qatar with the Qatari prime minister in an effort to find a peace formula both Israel and Hamas can agree on. (Egypt and Qatar have been relaying proposals to Hamas leaders.)

So far, however, Israel and Hamas disagree over a fundamental question: whether the cease-fire will be permanent or just a temporary pause to allow for an exchange of hostages taken from Israel for Palestinian prisoners.

The talks have been “progressing positively,” said Majed al-Ansari, the spokesman for Qatar’s Foreign Ministry, before the latest gathering. But, he added, “We are by no means out of the woods.”