At least 82 people reportedly died on Friday, the bloodiest day in some five weeks of unrest.
Two MPs and a senior Muslim cleric from Deraa have resigned in protest.
Friday's bloodshed, which came a day after President Bashar al-Assad scrapped decades of emergency rule, drew strong international condemnation.
Nearly 300 people are believed to have been killed since unrest erupted in the middle of last month.
Syria's state news agency has reported a limited number of protests in some provinces and described the violence as the work of armed criminal gangs.
With foreign journalists unable to get into Syria, accounts of casualties - carried by eyewitnesses, opposition activists and human rights groups - cannot be verified independently.
The BBC's Owen Bennett-Jones in Beirut says it appears that the government has made a deliberate decision to use live ammunition, to clear the streets and to impose order.
With many people in Syria now openly calling for an end to President Assad's rule, he says the government realises its survival is at stake and it is fighting hard.
'Carrying olive branches'
End Quote Unnamed woman who witnessed shooting in Damascus on FridayOne of the fallen people wasn't dead, he was injured and when someone tried to help, one security guard shot the injured person twice, to make sure he's dead”
"Currently we all are martyrs-to-be for the sake of our rights, of our dignity and for the dignity of the entire nation and the Syrian people," he told a crowd of mourners, who responded by shouting "God is great".
At least seven people were reportedly shot dead in the Douma and Barzeh, both districts of Damascus.
In Barzeh, mourners chanted "Where are you Assad? We're after your head".
They also taunted the president's brother, referring to Syrian territory occupied by Israel since the 1967 war: "Maher, you brute, take your dogs to the Golan Heights".
Many of Friday's deaths were reported to have occurred in Ezra and Douma as well as the central city of Homs.
A Homs resident who only gave his name as Mohammed told the BBC on Saturday people were afraid to leave their homes to attend funerals in case they were shot.
"Today Homs is empty, there nobody outside," he said. "They arrest anybody they find outside and they are now once again starting to shoot and kill anyone who goes outside. Homs is a ghost city.
He said the authorities had put a cordon around Homs and were blocking food supplies to this city of 700,000 people.
One unnamed Damascus resident has given the BBC a harrowing account of how she and others came under fire.
"I was very close, five metres away," she said.
"I saw more than six people falling to the ground. Anyone close to them who attempted to help was shot at too. One of the fallen people wasn't dead, he was injured and when someone tried to help, one security guard shot the injured person twice, to make sure he's dead.
"We all started running. Two people running next to me were gunned down."
Attending a protest rally in the city's Harista district on Saturday, she saw more shooting but it was "nothing like [Friday] because people didn't hang around but ran away quickly".
The protesters were peaceful, she stressed. "They were carrying olive branches and [asking] for freedom and democracy."
Resignations One of the resigning MPs, Naser al-Hariri, told al-Jazeera TV: "After I have failed to protect my sons from the treacherous shots there is no point in me staying in parliament."
The second MP, Khalil al-Rifaei, said he could not "protect the people who brought me to parliament", and urged President Assad to intervene to stop the violence.
Rezq Abdulrahman Abazeid, the government-appointed mufti or Muslim preacher for Deraa province, said he was resigning "as a result of the fall of victims and martyrs by police fire".
"When they announce at high levels that [protesters] will not be shot at, we see that the truth on the ground is not like that," he told al-Jazeera.
US President Barack Obama joined a chorus of international condemnation of Friday's attacks on protesters, calling for an end to the "outrageous use of violence to quell protests".
An unnamed Syrian official rejected criticism by Mr Obama, telling the Syrian state news agency Sana it was "not based on an objective vision of the reality on the ground".
Sana said security forces had only used tear gas and water cannon to prevent clashes on Friday.