Urgent calls grew on Sunday for foreign nationals to leave Lebanon, which would be on the front line of a regional war, as Iran and its allies ready their response to high-profile killings blamed on Israel.

While diplomats worked to avert a feared conflagration, French President Emmanuel Macron and Jordan's King Abdullah II said a regional military escalation must be avoided "at all costs", the French presidency said after they held a phone call.

With major military action from Lebanon's Iran-backed Hezbollah movement and others widely expected, Israeli Defence Minister Yoav Gallant said: "If they dare to attack us, they will pay a heavy price."

The nearly 10-month-old war in Gaza between Israel and Hamas has already led to a violent fallout which has become routine around the region, with more deaths on Sunday.

Near the Israeli commercial hub of Tel Aviv, medics and police said two people were killed in a stabbing attack.

The assailant, a Palestinian from the Israeli-occupied West Bank, was "neutralised" by police and taken to hospital, where he was pronounced dead.

Lebanon's Hezbollah, which has traded near-daily fire with Israeli forces since the Gaza war broke out in October, claimed several attacks on Israeli military positions Sunday.

Lebanon's official National News Agency reported Israeli strikes on various areas of south Lebanon, after Hezbollah said its fighters had fired a new barrage of rockets at Israel's north.

The Israeli military said most of the 30 projectiles launched from Lebanon were intercepted.

Military spokesman Rear Admiral Daniel Hagari said that "as of now" Israel's policy for protecting civilians has not changed.

Yemen's Iran-backed Huthi rebels on Sunday claimed a strike on a cargo ship in the Gulf of Aden. It was the first such attack since Israel struck the rebel-controlled Hodeida port last month in retaliation for a Huthi drone strike on Tel Aviv.

Saudi Arabia and France became the latest of several countries calling on their citizens to leave Lebanon.

"In a highly volatile security context", the foreign ministry in Paris "urgently asked" its nationals to avoid travelling to Lebanon and suggested those already in the country leave "as soon as possible".

France also urged its nationals living in Iran to "temporarily leave".

Several Western airlines have suspended flights to Lebanon and other airports in the region.

Qatar Airways said the Doha-Beirut route would "operate exclusively during daylight hours" at least until Monday.

Wednesday's assassination of Hamas political leader Ismail Haniyeh in Tehran, hours after the Israeli killing of Hezbollah's military chief Fuad Shukr in Beirut, has triggered vows of vengeance from Iran and the "axis of resistance" of Tehran-backed armed groups.

Israel, accused by Hamas, Iran and others of killing Haniyeh, has not directly commented on the attack.

Israel has vowed to destroy Hamas in retaliation for its unprecedented October 7 attack on Israel which resulted in the deaths of 1,197 people, mostly civilians, according to an AFP tally based on Israeli official 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 campaign has killed at least 39,583 people in Gaza, according to the territory's health ministry, which does not give details of civilian and militant deaths.

Haniyeh was Hamas's lead negotiator in efforts to end the war. His killing, and that of Shukr, "does not suggest Israel is sincerely interested in a ceasefire", said Middle East expert Andreas Krieg.

Qatari, Egyptian and US mediators have for months tried to broker a truce and hostage-release deal.

In the deadliest incident on Sunday in Gaza, the Civil Defence agency said an Israeli strike hit two Gaza City schools housing displaced people in the territory's north, killing at least 30 people.

This brings to at least 11 the number of schools hit in Gaza since July 6.

Israel's army confirmed the latest strike, saying the schools were used by Hamas.

Analysts have told AFP that a joint but measured action from Iran and its allies was likely, while Tehran said it expects Hezbollah to hit deeper inside Israel and no longer be confined to military targets.

Israel's ally the United States said it was moving additional warships and fighter jets to the region.

In an interview with ABC News, White House deputy national security adviser Jon Finer said the United States was "doing everything possible to make sure that this situation does not boil over".

As part of those efforts it is "so urgent" that a Gaza ceasefire deal be reached, Finer said.

Secretary of State Antony Blinken emphasised the need to calm regional tensions in a call with the Prime Minister Mohamed Shia al-Sudani of Iraq, where some Iran-aligned groups targeted US troops earlier in the Gaza war.

Jordanian Foreign Minister Ayman Safadi made a rare visit to Tehran. He held "consultations" with Iran's acting top diplomat Ali Bagheri and met President Masoud Pezeshkian, local media reported.

The G7 group of democracies convened by videoconference to discuss the Middle East and expressed "strong concern" over the threat of escalation, Italy's Foreign Minister Antonio Tajani said.

Haniyeh's killing "has brought the Middle East to its moment of greatest peril in years", the International Crisis Group (ICG) think tank said in a report.

The ICG said that securing "a long overdue ceasefire" in Gaza was "the best way of meaningfully reducing tensions in the region".

Hamas officials but also some analysts as well as protesters in Israel have accused Netanyahu of prolonging the war.

"Peace is made with the strong not with the weak," Netanyahu said Sunday at a ceremony in Jerusalem. (AFP)

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