At least 12 people were killed, including a woman and a child, by launching rockets by government forces against the city of Duma, northeast of Damascus, the Syrian Observatory for Human Rights reported.
The NGO noted that there are also an unknown number of wounded, some of them serious, so he did not rule out the death toll increases, Efe reported.
Duma is the largest city in the region of East Guta, the main opposition stronghold on the outskirts of Damascus.
Last Friday, at least 57 people were killed and dozens wounded by launching twelve rounds by the troops of the regime against a market Duma, according to figures from the Observatory.
That attack coincided with a meeting in Vienna of the main countries involved in the Syrian conflict, such as the US, Iran, Russia and Turkey, which did not attend any Syrian representative, or the government or the opposition.
At that meeting, participants agreed to give a boost to peace in Syria, which is the scene of conflict for more than four years has killed more than 250,000 people, according to the Observatory ago.