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.

An Israeli strike on Yemen's rebel-held Hodeida port has caused at least $20 million in damage, adding to losses due to the destruction of fuel storage facilities, a port official has said.

The July 20 attack on Hodeida, the main harbour under the control of the Iran-backed Huthi rebels, destroyed most of the port's oil storage capacity and triggered a massive inferno that burned for days.

Nine people were killed in the strike, according to the rebels, the first attack ever claimed by Israel on Yemen which came a day after a deadly Huthi attack on Israel.

Hezbollah has evacuated positions in south and east Lebanon after Israeli threats of reprisals for a deadly strike on the annexed Golan Heights, a source close to the group said Sunday.

Israeli Defence Minister Yoav Gallant vowed to "hit the enemy hard" a day after rocket fire from Lebanon killed 12 minors in Majdal Shams, again raisings fears that the war in Gaza will spread.

Yuval Freilich's dream of Olympic glory in Paris lasted just nine minutes on Sunday, which the Israeli fencer told AFP was a "huge disappointment".

But he reflected that, "given the larger picture...it's a positive experience."

The 29-year-old has been accustomed to making history by becoming both the first Israeli man to be crowned European champion and the first to qualify in the epee for an Olympics.

France has opened an investigation into death threats against three Israeli athletes as well as possible anti-Semitic hate crimes during a football match, the Paris prosecutor's office said on Sunday.

The death threats were reported by Interior Minister Gerald Darmanin and the investigation will be led by the national anti-online hate body, the prosectuors' office said in a statement.

Israel on Thursday warned France about cyber harrassment of its athletes and leaks of personal data that it blamed on Iran-backed groups.

Palestinian swimmer Yazan Al Bawwab hopes his appearance at the Paris Olympics will help boost opportunities for athletes from the war-torn territory.

Al Bawwab, 24, who was born in Saudi Arabia and lives in Dubai in the United Arab Emirates, competed in the heats of the men's 100m backstroke on Sunday.

It is his second appearance in the Olympics, following on from Tokyo, and he has two gold medals from the Arab Games.

The Golan Heights, a rocky plateau where 12 youths were killed Saturday amid clashes between Lebanon's Hezbollah and Israeli forces, is a strategic territory partially captured by Israel from Syria.

Following the conquest of about two-thirds of the plateau during the 1967 Arab-Israeli war, Israel in 1981 annexed the area in a move not recognised by the international community, with the exception of the United States since 2019.

Weeping men carried small coffins at a funeral ceremony attended by thousands from the Druze community on Sunday for many of the 12 youths killed in a rocket attack on the Israeli annexed Golan Heights.

The Israeli military said they were struck on Saturday by an Iranian-made rocket carrying a 50-kilogramme warhead that Lebanon's Iran-backed Hezbollah group fired at a football field in the Druze Arab town of Majdal Shams.

Hezbollah has denied responsibility for the strike.

Local authorities said the dead were aged between 10 and 16.

Iran's supreme leader Ayatollah Ali Khamenei gave Sunday his official endorsement of Masoud Pezeshkian as the Islamic republic's ninth president, following snap elections won by the reformist camp's candidate.

In a message read by the director of Khamenei's office, he said: "I endorse the vote (for) the wise, honest, popular and scholarly Mr Pezeshkian, and I am appointing him as the president of the Islamic Republic of Iran".

The new reformist president is due to be sworn in before parliament on Tuesday.

Israel vowed on Sunday to "hit the enemy hard" after rocket fire from Lebanon killed 12 young people in the Israeli-annexed Golan Heights and fanned fears that the war in Gaza will spread.

Iran warned Israel that any new military "adventures" in Lebanon could lead to "unforeseen consequences".

UN Secretary-General Antonio Guterres condemned Saturday's rocket fire and called on all parties to "exercise maximum restraint".