Syria's air defence system has been activated against an "Israeli aggression" within Syria, state news agency Sana said late Tuesday.
Israeli planes arrived from Lebanese air space, said Sana, which gave no indication of any deaths or damage.
The Syrian Observatory for Human Rights, a Britain-based war monitor, reported "violent explosions felt in Damascus and around the city, followed by Israeli strikes on military positions" of the Syrian army.
"Air strikes also took place in the south of Homs province and in the border zone between Homs and Tartus," Observatory chief Rami Abdul Rahman told AFP.
The Israeli army, which rarely acknowledges its strikes in Syria, told AFP it would not comment on "information coming from abroad".
Since the start of the war in neighbouring Syria in 2011, Israel has carried out hundreds of air strikes on Syrian territory, targeting regime positions as well as Iranian forces and members of Lebanon's Hezbollah movement.