In the eastern province of Deir Ezzor, three civilians were killed in shelling and gunfire while four rebels were killed when a rocket hit their vehicle, the Syrian Observatory for Human Rights said.
And in Tafas, in southern Daraa province, six people were killed including five who died when shelling hit their car. In Damascus province, three civilians were killed in shelling on the suburb of Douma and one in Al-Madamiyeh, the Britain-based group said.
Shelling and gunfire killed two civilians in the central province of Hama, four in the northern province of Aleppo, and one woman in the northwest province of Idlib. Two civilians were killed when regime forces shelled the rebel-held town of Rastan in Homs province, the Observatory said, while three civilians and one rebel were killed in Homs city.
Opposition activists reported 15 villagers were killed by gunfire at dawn in a Sunni village in the central province of Hama. The Observatory cited the same figure, but said it was unable to confirm their identities.
The rights group emphasised the killings occurred after the assassination the previous night of three Alawites from the surrounding area. An activist in Homs told AFP via Skype that many civilians remained trapped in the shelling of the Jurat al-Shiah, Khaldiyeh and Old City neighbourhoods of Syria's third-largest city.
"Many neighbourhoods of Homs are still under siege, and it is really hard for us to get food or medicines in," said the activist who uses the pseudonym Khaled al-Tellawy.
"Field doctors are amputating the limbs of the injured because they have no equipment to treat them with, and they can't be smuggled out." "We need the Red Crescent to come into Homs, we have practically no food or medicine," an activist known as Abu Bilal told AFP via Skype, adding residents of besieged neighbourhoods were sharing whatever food was available.