Military sources say four soldiers were killed and two others were kidnapped after armed men attacked a military post in the southern city of Deraa on Friday.
Rights activists, however, say that Syrian security forces shot and killed 16 protesters in the city.
There are also reports of clashes in the eastern city of Latakia, where witnesses say security forces opened fire on protesters, injuring at least five people.
Also in the city of Homs, a dozen people, including three security forces were killed.
Hundreds of Syrians also took to the streets in Damascus, Qamishli and Baniyas to express solidarity with the people of Deraa.
Activists say hundreds of people have been killed since the beginning of protests in Deraa and several other cities in mid-March.
While the opposition accuses security forces of killing protesters, the government blames armed groups and foreign element for the violence saying security forces have been given clear instructions not to hurt civilians.
On Wednesday, Syrian military officials announced that members of a terrorist group were behind the deadly clashes in Deraa.
The terrorists have confessed that they had received money from foreign organizations to kill government forces and cause chaos in the city, according to the state television.
So far, over 230 members of Syria’s ruling Baath party have resigned in protest at the killings.