In the latest violence to hit the country Friday, at least 100 people were killed in incidents across the country, according to the opposition Local Coordination Committees of Syria.
On Thursday a suicide bomber struck one of the main mosques in Damascus, killing a top Sunni cleric and longtime al-Assad supporter, Syrian state-run media.
Mohammad Said Ramadan al-Bouti was teaching religious class at the mosque when he was killed during the blast, state-run media reported.
There was no immediate claim of responsibility for the attack, but al-Bouti is hated among rebels for his support of al-Assad.
In one of his final sermons at the Umayyad, or Great Mosque, of Damascus, al-Bouti called on Syrians to stand by the government and condemned rebels as "terrorists."
As has become common in violent attacks that kill civilians, the government and the opposition accused one another of being behind the attack.
The LCC said the area where the mosque sits is near al-Assad's party headquarters.
"The whole area was under the full control of the regime forces with much military reinforcement," the LCC said.
The government, meanwhile, accused rebels of being behind the attack.
Sunni Arabs make up the majority of Syria's population and are dominant in the opposition, but some support the government, controlled by Alawites -- an offshoot of Shiitism.
More than 70,000 people have died in Syria since unrest began two years ago, the United Nations has said.