Syrian army forces arrested a leading group of the armed organizations in the north-western town of Jisr al-Shaghur, the official SANA news agency reported Saturday.
The army began operations on Friday "to restore security" in Jisr al-Shaghur, located near the Turkish border, DPA reported.
SANA also reported that "eight people - civilians, police and security forces - were killed Friday by armed terrorist gangs which exploited some gatherings in different areas."
Tens of thousands of anti-government protesters took part in rallies across the country amid security crackdown, calling for the ouster of President Bashar al-Assad.
At least 25 people were killed, the Syrian Observatory rights group said, when security used force and live ammunition against protesters.
Protesters dubbed the day "Friday of Tribes," in the hope of strengthening tribal support for the demonstrations.
At least 1,300 people have been killed and over 10,000 detained since anti-government protests began mid-March, according to rights groups and activists. Due to restrictions on journalists in the country, reports are difficult to verify.
The White House strongly condemned the deadly violence and reiterated US support for a UN resolution being circulated among Security Council members.
"There must be an immediate end to the brutality and violence," spokesman Jay Carney said in a statement.