Opposition activists say Syrian warplanes bombed targets near Damascus on Friday, a day after an explosion in the capital left at least nine people dead.
The Britain-based Syrian Observatory for Human Rights says government shelling is underway in areas including Douma, a rebel stronghold.
The state-run SANA news news agency says "terrorists" detonated explosives at a gas station in a Damascus neighborhood, on Thursday.
There was no immediate claim of responsibility.
Civil war between rebels and the Assad government has gripped Syria since evolving from peaceful anti-government protests in March 2011.
The United Nations estimates 60,000 people have died in Syrian fighting, a figure that surpasses opposition estimates by about one-third.