Rami Abdel Rahman of the Syrian Observatory for Human Rights said that of the 83 deaths nationwide, 63 people were killed in shelling and other violence in Homs province.
Fifty-three were killed in Homs city, which has been under a relentless bombardment by regime forces for the past six days, he said.
Of these, Abdel Rahman said 35 civilians died in the Baba Amr neighbourhood of Homs and 11 were killed when a shell slammed into their house in the protest hub's Inshaat district.
He added that seven other people died in the city's Khaldiyeh and Karm el-Zeytoun neighbourhoods.
Ten more people, five from the same family, died in shelling and heavy gunfire as regime troops pushed forth with a more than week-long assault on the town of Zabadani near the Syrian capital, Abdel Rahman added.
"They are trying to choke the town before storming it," he said. "Residents are fleeing to Bludan and other nearby villages."
Elsewhere, seven security forces members were killed when rebels ambushed two buses near the southern town of Daraa, cradle of the revolt against the regime of President Bashar al-Assad.
Among other deaths in the armed forces, a military colonel was killed at his home in Rastan, in Homs province.
Four other civilians, including a young woman, were killed in the northwestern province of Idlib, and a man died of wounds he suffered the day before in Daraa.