The attacks began at dawn, when the army stormed and captured the village of Samdaniya al Gharbiya, near the border with the Occupied Palestine.
Under cover of rain and fog, government troops pushed towards the strategic town of Hamdanieh, in the Syrian Golan Heights, which they lost two years ago.
"They staged a large-scale attack under cover of heavy fog, where you can hardly see someone only a few metres away from you, on the two villages," said Abu Yaha, a spokesman for the Furqan Brigade, a terrorist group in the area.
The attacks came in Qunaitra province, a sensitive piece of territory around 70 km (40 miles) southwest of the capital, Damascus, Reuters reported.
The offensive is the government's first in the south since Russia joined the war on Sept. 30 in support of its ally, Syrian President Bashar Assad. Thursday's attacks came just days after an assault on the town of Sheikh Maksin that saw Russia's heaviest bombing campaign so far in the south.