Syrian forces loyal to President Bashar al-Assad are reported to have shot dead five protesters after Friday prayers.
The government, meanwhile, said an army officer was killed as violence marred a ceasefire brokered by peace envoy Kofi Annan.
At the United Nations, Russia criticised a US drafted resolution authorising an advance team to monitor the fragile ceasefire.
The truce aims to end 13 months of bloodshed during the uprising against Mr Assad.
Syrians took to the streets across the country in small demonstrations, trusting that the two-day-old truce would protect them from the army bullets.
Activists said security forces came out in strength in many cities to prevent protesters mounting major rallies against Mr Assad.
The plan of UN Arab League envoy Mr Annan says the government should have pulled its troops back.
Protesters questioned Mr Assad's commitment to the peace plan that he has accepted.
In the Qadam district of Damascus, they held up a placard saying: "Bashar may be able to laugh at the whole world - except for the Syrian people".
Soldiers also shot one person dead as worshippers left a mosque in Nawa in the southern province of Deraa, where the uprising began in March 2011.
Security forces killed a fourth in the town of Salqeen in the northwestern province of Idlib, opposition activists said, and a fifth died in Deraya, Damascus province.
However, Syria's state news agency SANA blamed two of the deaths on the opposition, saying an "armed terrorist group" shot dead the man in Salqeen and attributing the death of one Hama protester to a shot fired by a fellow demonstrator.
SANA also said "terrorists" shot an army major dead as he drove to work.
Armed groups were seeking to "destroy any effort to find a political solution to the crisis" in Syria, it said.
Reports from Syria cannot be independently verified as state authorities have barred international journalists and rights groups.
World leaders earlier welcomed the halt in fighting, which had threatened to spill over into neighbouring countries, with UN Secretary General Ban Ki-moon saying the situation looked calmer.
"The world is watching, however, with sceptical eyes since many promises previously made by the government of Syria have not been kept," he told a news conference in Geneva.
Mr Annan wants up to 250 unarmed UN observers in Syria.
Ambassador Vitaly Churkin of Russia, which has supported the Syrian government, said the 15-member Security Council could today adopt a resolution authorising the deployment.
"The full-fledged mission will take some time to deploy ... If we are able to put 20 or 30 monitors (there) early next week, very good," Mr Churkin said.
"If we are able to put more in the next few days that's even better."
A draft resolution by the United States included a vague threat of future action against Damascus.
It said the council "expresses its determination, in the event that the Syrian government does not implement its commitments, to consider further measures as appropriate".
Along with the withdrawal of forces from population centres, Mr Annan's six-point plan calls for talks with the opposition aimed at a "political transition", the release of political prisoners, access for humanitarian aid and journalists, and for the authorities to "respect freedom of association and the right to demonstrate peacefully".