Israel struck Syrian army targets on the Golan Heights on Sunday, sources on both sides said, and Israel said it was retaliating for cross-border rocket fire from the Syrian war next door, Reuters reported.
Rebel sources in southern Syria and a British-based monitoring group said at least three Israeli air strikes had hit army sites near the frontier with the Israeli-occupied part of the strategic plateau.
Israel's army confirmed it had targeted two Syrian army posts, but said it used artillery fire, not air strikes, in response to "errant" rockets from inside Syria landing on its territory.
Fighting between government forces and rebels in the Quneitra area of the Syrian Golan Heights has intensified in recent days.
It was the first Israeli fire on southern Syria in more than a month. Israel has attacked Syrian armed forces and arch-foe Lebanese Hezbollah, a Damascus ally, during the four-year-old civil war in its hostile neighbor.
Last month Israel waged its heaviest bombardment since the conflict began, killing Palestinian militants in response to cross-border fire.
It has said it holds the Syrian government responsible for any spillover of violence.
Diplomatic efforts to find a solution to the Syrian war have intensified as record numbers of migrants travel to Europe, and as Russia steps up its military aid for ally President Bashar al-Assad.
Prime Minister Benjamin Netanyahu and President Vladimir Putin on Monday agreed to set up an Israeli-Russian coordination team to prevent the countries accidentally trading fire in Syria.
Israel captured the western Golan in the 1967 Middle East war and annexed it, a move not recognized internationally.