The fighting in Zabadani, a town near Damascus and the last rebel stronghold in the area, is part of the larger battle for control of the mountainous Qalamoun region, stretching from the Syrian capital to the border with Lebanon.
President Bashar Assad's forces, backed by Lebanese militant Hezbollah fighters, launched an offensive in Qalamoun in mid-November, ousting rebels from the area and cutting their supply routes from Lebanon.
According to the Britain-based Syrian Observatory for Human Rights, which gathers reports from opposition activists on the ground, the latest bout of clashes killed 14 rebels and an unknown number of soldiers. The Syrian government does not publicize its casualty figures in the 3-year-old conflict.
Rebels in the area have been firing mortars into the capital, the seat of Assad's government. While mortar attacks have subsided since the fall of two opposition strongholds in Qalamoun, rebels are still able to strike the heart of the capital and other cities.
Syrian state news agency SANA said mortar fire killed a man and wounded two teachers Thursday in central Damascus. Mortar fire in the town of Jaramana just outside the city killed a child and wounded 22 people, the agency said.
"The deliberate targeting of civilians is a war crime, and if carried out in a widespread or systematic way amounts to crimes against humanity," the group said. It called on the UN Security Council, which has been unable to stop the conflict in Syria, to impose an arms embargo on any groups implicated in systematic human rights abuses, including the Syrian government.
