Reports emerging from the Israeli and Syrian armies give conflicting numbers and information. The Syrian army claims that the Israeli air strikes targeted a civilian vehicle and resulted in killing five people.
The Israeli army claims that the air strikes were well aimed, and killed four Palestinians, who the Israeli authorities claim were responsible for an alleged rocket attack that came from Syrian territories.
"We know of at least four of them who were killed," the official said in a statement.
Israel warned the Syrian government on Thursday that it will respond to the four rockets fired from its territory into north Israel.
The retaliatory Israeli air strikes took place Thursday night.
The identity of the five civilian victims hasn't been released yet. Syrian state television, quoting an army source, said the attack took place in a village near Quneitra, near the Israeli-occupied section of the Golan Heights region but gave no further details.
“This was the work of Islamic Jihad, an organisation financed and working for Iran, and we consider the Syrian government responsible for the firing and it will suffer the consequences,” said the Israeli army on Thursday morning.
The Israeli authorities say the rockets were fired by an Iranian-backed Palestinian faction. The rockets landed in an Israeli village, setting off fires but causing no casualties.
No group has claimed responsibility for the attack.
The Syrian army initially said the air strikes killed one soldier and wounded seven.
Israeli air strikes on Golan Heights on Thursday night was the heaviest Israeli bombardment since the start of Syria's four-year-old civil war, according to the UK based Syrian observatory for Human Rights.
Israeli Defence Minister Moshe Yaalon in a statement accused Iran of seeking to "open a new terrorist front against Israel on the Golan Heights." Iran has been backing the Syrian regime all through the four year long civil war that killed more that 300,000 people and displaced more than 7.2 million people.
Yaalon challenged Tehran not to test "Israel’s determination".
"What we’ve seen overnight is the prelude of things to come, following the signing of the nuclear agreement and the lifting of sanctions. An Iran that can funnel additional funds and weapons to terror organizations operating against Israel and Western interests in the region," Yaalon said
Israel invaded the western part of the Golan Heights in the 1967 and annexed it, a move not recognized internationally.