Assad's army has taken control of the rebel stronghold of Qusayr, a town on the Lebanese border that gives Syrian forces access to the coast from Damascus.
At least 30 people were killed in the government's assault, which reportedly involved help from Hezbollah fighters, though state TV was reporting that 70 "terrorists" died in the attack, BBC News reported.
The strike involved tanks and warplanes pummeling Qusayr with airstrikes and artillery, and is part of Assad's larger strategy to re-take control of towns along the Lebanese border, according to the Associated Press.
"The army is hitting Qusayr with tanks and artillery form the north and east while Hezbollah is firing mortar rounds and multiple rocket launchers from the south and west," activist Hadi Abdallah told Reuters. "Most of the dead are civilians killed by the shelling."
The Syrian National Council denounced the "barbaric and destructive bombing" and said Assad's Hezbollah-aided forces were aiming to "invade the town and wipe it and its residents off the map."
The assault comes on the heels of a rare interview with Assad in which the dictator said that his government was not using "fighters from outside of Syria, of other nationalities, and needs no support from any Arab or foreign state."
He also reiterated that he would not step down from power before the country's elections in 2014.
Syria's opposition condemned "attempts to invade" the town, which it said could render US-Russian efforts to organize a peace conference "meaningless."