Israel's far-right Finance Minister Bezalel Smotrich has ordered the seizure of 100 million shekels ($26 million) of tax funds intended for the Palestinian Authority, saying it would be used to pay for Israeli victims of terrorism.

Diplomatic pressure mounted Monday to avoid an escalation between Iran and Israel following high-profile killings that have sent regional tensions soaring, while numerous governments urged their citizens to leave Lebanon.

Israeli Prime Minister Benjamin Netanyahu said late Sunday that his country was "determined to stand against" Iran and its allied armed groups "on all fronts".

Iran said Monday it has the "legal right" to respond to the assassination in Tehran last week of Hamas chief Ismail Haniyeh, an attack blamed on Israel amid the Gaza war.

"No one has the right to doubt Iran's legal right to punish the Zionist regime", Iranian foreign ministry spokesman Nasser Kanani told a regular news conference.

Israel's army said it had not changed "as of now" its policy for protecting civilians, as Iran and Hezbollah are expected to avenge killings blamed on Israel of two senior members.

"I would like to refer tonight to the various reports and rumors that we are on alert for the enemy's response to the territory of the State of Israel," military spokesman Rear Admiral Daniel Hagari said Sunday in an online briefing to journalists.

Travelers waited in long lines at Beirut airport on Sunday, some after cutting summer holidays short, as airlines have cancelled flights and fears have grown of all-out war between Israel and Hezbollah.

"I'm not happy to leave. I wanted to spend the whole summer in Lebanon then go back to work" in France, said Joelle Sfeir from the crowded departures hall at Beirut airport.

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

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

The UK government has urged its citizens in Lebanon to leave the country immediately, amid fears of all-out war between Israel and Hezbollah and a broader regional conflict.

The U S. embassy in Lebanon has urged its citizens to leave Lebanon on "any ticket available," amid fears of all-out war between Israel and Hezbollah and a broader regional conflict.

Hezbollah said overnight it had launched dozens of Katyusha rockets at northern Israel.

The Iran-backed group said its latest attack, on Beit Hillel in northern Israel, was in response to Israel's attacks on Kfarkela and Deir Siriane in south Lebanon which, it said, had injured civilians there.

Lebanon on Sunday marks four years since a catastrophic explosion at Beirut's port killed more than 220 people, with fears of all-out war between Israel and Hezbollah hanging heavy over the grim commemoration.

Several marches are set to converge on the port in the afternoon to remember the victims and demand justice.