Israel said on Sunday an airstrike against an arm of Iran's Revolutionary Guards in Syria that it accused of planning "­killer drone attacks" showed Tehran that its forces were vulnerable anywhere.

A senior Revolutionary Guards commander denied that Iranian targets had been hit late on Saturday and said its military "advisory centers have not been harmed," the semi-official ILNA news agency reported.

The Israeli military said its aircraft struck "Iranian Quds Force operatives and Shiite militias which were ­preparing to advance attack plans targeting sites in Israel from within Syria over the last number of days."

The elite Quds Force is the overseas arm of Iran's Revolutionary Guards. 

Israeli military spokesperson Jonathan Conricus told reporters the forces on Thursday had been preparing to launch "killer drones" armed with explosives at northern Israel.

Israeli Prime Minister Benjamin Netanyahu said the military had thwarted the planned Iranian attack.

"Iran has no immunity anywhere. Our forces operate in every sector against the Iranian aggression," he said on Twitter. 

"If someone rises up to kill you, kill him first."

Syrian state media said Syrian air defenses intercepted "hostile targets" over Damascus, the capital, on Saturday night. 

Witnesses in Damascus said they heard and saw explosions in the sky.

The Syrian army said in a statement that "the majority of the Israeli missiles were destroyed before reaching their targets." Conricus, however, said the impact of the Israeli strikes was "significant."

Israel made no comment on what the Lebanese army and Hezbollah said was the crash of two Israeli drones in the southern suburbs of Beirut early on Sunday.