The missile fire set fire to a tanker as it was unloading in the Inshaat neighbourhood of Homs, which is the provincial capital and largely under government control, SANA said.
"The rocket fire came from Talbisseh in northern Homs province where extremist groups led by (Al-Qaeda affiliate) Al-Nusra Front are located," the agency added.
The Syrian Observatory for Human Rights, a Britain-based monitor, also reported five dead in a blast at the petrol station, with 40 people injured.
The monitor said the toll was likely to rise because a number of the wounded were in serious condition.
Most of the central Homs province is under regime control, though rebels are present in Homs city's Waer district and a few other areas in the province.
The Islamic State group also controls parts of eastern Homs province, including the ancient town of Palmyra.