Syrian air defences engaged an "enemy target" near the border with Lebanon west of Damascus overnight, state news agency SANA reported on Saturday.
"Our air defences confronted an enemy target that penetrated airspace above the area of Deir al-Ashair in the Damascus countryside," SANA said.
The Syrian Observatory for Human Rights confirmed air defences had launched missiles, but said it was unclear what they were targeting or whether there was any target at all.
The Britain-based war monitor said Lebanese Shiite militant group Hezbollah, which has been backing the Damascus government in Syria's seven-year civil war, was present in the area.
Israel has carried out numerous raids in Syria in recent years, targeting government forces, Hezbollah and Iran, another ally of Damascus.
Last week, SANA said Syrian air defences confronted another "enemy attack" west of Damascus. Then too the Observatory, which relies on sources inside Syria for its information, said it was unable to determine who was responsible.
Last month, Syria accused Israel of bombing a military post in the northern province of Aleppo, where the Observatory reported at least nine pro-regime fighters died.