Shells landed near a Damascus airbase after being fired from an "unknown source" late on Tuesday, Syrian state media said.
A loud explosion was heard after three shells were fired near Mezzeh military airport, news agency Sana said. It said there were no casualties.
Investigators were at the base to "determine the source of the shells". The incident comes a day after Syrian authorities celebrated a year since Bashar Al Assad's downfall, with a parade beginning at Mezzeh airport.
Authorities say the base was also where former president Al Assad staged his escape from Damascus, first fleeing to a Russian base in Hmeimim before being granted asylum in Russia. There is talk of turning Mezzeh into a civilian airport.
Several outbreaks of fighting, notably involving the Alawite, Druze and Kurdish minorities, have set back the new regime's efforts to consolidate power in Syria. But unrest in Damascus has been relatively rare.
ISIS was blamed for a church bombing in Damascus that killed about 25 people in June. Israel also bombed the capital in July and has previously attacked the military airport.
President Ahmad Al Shara used Monday's anniversary celebrations to pledge a "strong and just" nation would be rebuilt after a 13-year civil war, which ended with the rebel offensive that toppled Bashar Al Assad.
