The Syrian Observatory for Human Rights said rebels were ambushed at dawn by Syrian military forces.
Syria's official news agency SANA said soldiers killed rebels affiliated with al-Qaida al-Nusra Front. The news agency said all rebels were killed and soldiers confiscated machine guns and rocket-propelled grenades found in the rebels' possession.
The observatory also reported clashes with Syrian soldiers in areas surrounding Damascus. Two warplanes bombed parts of Homs and fired a rocket at a village near Hama. In Aleppo, rebel units strengthened their positions after seizing a military airport.
Eighteen Syrian civilians were killed and dozens injured Tuesday in a car bombing in the Damascus suburb of Jarmana.
"Terrorists blew up a car bomb with big quantities of explosives in the area, which is crowded with inhabitants, claiming the lives of 18 citizens, among them three children, and injuring 56," a police source told SANA.
The United Nations estimates more than 100,000 people have been killed in the civil war in Syria since March 2011. Thousands are unaccounted for and millions have been displaced.