Israeli Prime Minister Benjamin Netanyahu said the recent air strikes by his country inside Syria targeted weapons bound for Lebanon's Hezbollah, and the same would be done again if necessary.

Israeli warplanes struck several targets in Syria early on Friday, prompting retaliatory missile launches, in one of the most serious incidents between the two countries in recent years.

Syria's military said it had downed an Israeli plane and hit another as they were carrying out pre-dawn strikes near the famed desert city of Palmyra which was recaptured from the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) this month.

The Israeli army denied that any planes had been hit.

Netanyahu said in footage aired on Israeli television networks: "When we identify attempts to transfer advanced weapons to Hezbollah and we have intelligence and it is operationally feasible, we act to prevent it."

"That's how it was yesterday and that's how we shall continue to act," he added.

The Israeli air force said earlier that it had carried out several strikes on Syria overnight, but that none of the ground-to-air missiles fired by Syrian forces in response had hit Israeli aircraft.

It was an unusual confirmation by Israel of air raids inside Syria.

"Overnight ... aircraft targeted several targets in Syria," an Israeli army statement said on Friday.

"Several anti-aircraft missiles were launched from Syria following the mission and [army] aerial defence systems intercepted one of the missiles."

The Syrian army described the attack as an act of aggression that aided the ISIL group, which is fighting against the Syrian government.

Rocket sirens sounded in Israeli settlements in the Jordan valley, the military said and two witnesses heard an explosion a few minutes later, Reuters news agency reported.

A Jordanian military source said shrapnel from one missile fell in the north of the kingdom without causing any casualties, according to AFP news agency.