(AFP) - Israeli Prime Minister Benjamin Netanyahu on Monday vowed a "severe" response to a deadly strike that killed 12 youths in the annexed Golan Heights, as diplomats raced to contain escalation between Israel and Hezbollah.

On a visit to the site of the deadly rocket strike in the town of Majdal Shams, Netanyahu said: "The State of Israel will not, and cannot, let this pass. Our response will come and it will be severe."

He was greeted by protests during the visit, which came after mourners gathered in the Druze Arab town to bury the last victim, 11-year-old Guevara Ibrahim.

Israel and the United States have blamed the strike on Lebanon's Iran-backed Hezbollah movement, which has traded near-daily fire with Israeli forces since the war in Gaza between Hamas militants and Israel began in early October.

Lebanese Foreign Minister Abdallah Bou Habib said a flurry of diplomatic activity has sought to contain the anticipated Israeli response.

"Israel will escalate in a limited way and Hezbollah will respond in a limited way... These are the assurances we've received," Bou Habib said in an interview with local broadcaster Al-Jadeed.

Several analysts told AFP that this was likely to be the case, with Israel wary of having to fight wars on two fronts.

The United States, France and others were trying to contain the escalation, Habib added, while Lebanese Prime Minister Najib Mikati said that "talks are ongoing with international, European and Arab sides to protect Lebanon and ward off dangers".

On Monday, White House National Security Council spokesman John Kirby said he was "confident" a broader war could be avoided.

New Iranian President Masoud Pezeshkian, whose country supports Hezbollah and Hamas, warned Israel against attacking Lebanon, which he said would be "a great mistake with heavy consequences".

Pezeshkian spoke with French President Emmanuel Macron on Monday, with the Elysee Palace saying Macron told his counterpart "all must be done to avoid a military escalation" and urged Tehran to "cease its support for destabilising actors".

Hezbollah has denied responsibility for the Majdal Shams rocket attack, though the group claimed multiple strikes on Israeli military positions that day.

Israel said Hezbollah fired a Falaq-1 Iranian rocket. This type of projectile is unguided and an analyst called them inaccurate weapons.

- Travel warning -

Hezbollah has evacuated some positions in south and east Lebanon, a source close to the group told AFP.

Some airlines, including Air France and Lufthansa, have suspended flights to and from Lebanon, with one Syrian-German traveller at Beirut airport telling AFP she was trying to find a new flight, “but they're all either packed or cancelled".

UK Foreign Secretary David Lammy, meanwhile, said on social media platform X that his government was "advising British nationals to leave Lebanon and not to travel to the country. This is a fast-moving situation."

On Monday, Hezbollah said it had launched "dozens of Katyusha rockets" at an Israeli military site following the killing of two of its fighters.

The group later claimed additional strikes against military positions in Israel's north. Official Lebanese media said a Syrian national died from wounds after an Israeli drone strike in southern Lebanon.

The cross-border violence has already killed more than 500 people in Lebanon, most of them fighters, and dozens of civilians and soldiers on the Israeli side.

Hezbollah has said its attacks are in support of Hamas, and that they would stop if a ceasefire was reached in Gaza, where war broke out on October 7 when the Palestinian militants attacked southern Israel.

Months of effort have failed to secure a ceasefire and hostage release deal, though mediators and Israeli negotiators met on Sunday in Rome to discuss the latest proposal.

"The negotiations on the main issues will continue in the coming days," an Israeli statement said.

Hamas, however, again accused Netanyahu of hindering a deal, saying in a statement that he had set new conditions in "a retreat" from an earlier draft.

The Hamas attack on southern Israel that started the war resulted in the deaths of 1,197 people, mostly civilians, according to an AFP tally based on official Israeli figures.

Militants also seized 251 hostages, 111 of whom are still held captive in Gaza, including 39 the military says are dead.

Israel's retaliatory military campaign in Gaza has killed at least 39,363 people, according to the health ministry in the Hamas-run territory, which does not provide details on civilian and militant deaths.

Hundreds of Gazans were fleeing the vicinity of the Al-Bureij refugee camp on Monday, witnesses said, after Israeli forces announced they would "operate forcefully" against fighters in the area.

- Soldiers detained -

Since the war began, rights activists, UN agencies and others have alleged abuses of Palestinians during Israeli detention.

On Monday, Israel's military said nine soldiers were being held for questioning in a case of suspected abuse of a detainee at a facility known to be holding Palestinians arrested from Gaza.

After the soldiers' detention, Israeli civilians protested outside a military base where the nine were being held, while several others -- also in an attempt to show support -- broke into the facility where the alleged abuse occurred.

"Take your hands off the reservists," Itamar Ben Gvir, Israel's far-right National Security Minister, wrote on X.

Other top Israeli officials, however, including Netanyahu and army chief Lieutenant-General Herzi Halevi, condemned the mob action.

"We are in the midst of a war, and actions of this type endanger the security of the state," Halevi said of the unrest.

© Agence France-Presse