On Friday, security forces fired on demonstrators in six towns and cities in a day of protests that activists declared a “Friday of Defiance,” killing at least 41 people. But a crackdown that has escalated over the past two weeks managed to subdue Dara’a and prevented many protesters from gathering in larger demonstrations, particularly on the outskirts of Damascus, activists and human rights groups said.

The worst violence was reported in Homs, where activists described a chaotic, bloody day, as tanks entered the town and areas around it. The government said 10 soldiers were killed there by what it described as “terrorists,” while activists said at least nine soldiers had defected to their side. Seventeen protesters were killed, they said.

Only in Baniyas and Jassem, a town near Dara’a, were demonstrators able to mass in larger protests. The resident in Baniyas said that protesters there had carried olive branches and red and white roses to hand to soldiers if the troops entered the city. They did, but only in the early hours of Saturday morning when many were sleeping.

The resident estimated that the crowd on Friday numbered at least 7,000, many of whom chanted for freedom, for the government’s fall and for the military to lift its siege of Dara’a.

The authorities have described Baniyas as a center of militant Islamists, and even some activists acknowledge that militants have a presence there, though by no means a majority. Civic leaders in Baniyas have insisted that the charge is a government ploy to stoke tensions between Sunni Muslims and Alawites, one of the fault lines in a country troubled by smoldering sectarian tensions between the Sunni Muslim majority and minorities of Christians and heterodox Muslim sects. Eastern Syria is populated by an ethnic minority, Kurds, who appeared to turn out in greater numbers in the streets on Friday.

Security forces, with the help of the military, also moved against the town of Zabadani, on the edge of Damascus. Mr. Tarif said that electricity and communications were cut to the town from Friday afternoon to Saturday afternoon, and checkpoints remained across the town. His group documented at least 80 arrests over that period, he said.

Mr. Tarif suggested that the assaults on Baniyas, Homs and Zabadani borrowed a page from the military’s attack on Dara’a and signaled the government’s intent to methodically move against centers of protest in the country with overwhelming force.