Israel also targeted positions inside Syria on Friday, in retaliation for mortar fire which had hit the Israeli-annexed Golan
An Israeli attack on a Syrian camp for pro-government National Defence Forces killed three fighters near the Golan Heights on Sunday, an official from the forces said.
The NDF official told AFP that two fighters were also wounded in the attack on the Al-Fawwar camp near Quneitra in southwestern Syria, adding that it was unclear whether the damage was inflicted by an air strike or shelling.
The Syrian Observatory for Human Rights monitoring group said the attack had targeted a "weapons warehouse" in the camp.
Israel's army declined to comment Sunday on the attack.
On Friday, the army said it targeted positions inside Syria in retaliation for mortar fire that hit the northern part of the Golan Heights.
In response to the projectiles fired from Syria that hit the northern Golan Heights earlier this evening, the IDF targeted the launch sites.
— IDF (@IDFSpokesperson) April 21, 2017
Syria's official news agency SANA said Israel had struck a Syrian army position in the province of Quneitra on the Golan plateau, "causing damage".
SANA, quoting a military official said that the Israeli "aggression came after an attempt by terrorists to infiltrate military positions in Quneitra countryside was foiled and the terrorists suffered heavy losses, which proves that Israel provides direct support to terrorist organisations".
The Syrian government labels rebel groups and militants fighting the government as "terrorists" and accuses Israel of backing them.
Israel has launched a number of air strikes against pro-government forces in Syria since the start of the war, with most targeting Lebanese militia Hezbollah.
Israel seized 1,200 square kilometres (460 square miles) of the Golan from Syria in the Six-Day War of 1967 and later annexed it in a move never recognised by the international community.
Around 510 square kilometres of the Golan are under Syrian control.
The two countries are still technically at war, although the border remained largely quiet for decades until 2011, when the Syrian conflict broke out.
The Israeli side is hit sporadically by what are usually deemed to be stray rounds and has recently taken to opening fire in retaliation.