Homs has been a frequent battleground in the 20-month Syrian civil war.
The Britain-based Syrian Observatory for Human Rights says the number of dead from the bombing may increase, because some of the wounded are in critical condition.
The Sana news agency did not refer to casualties. It said the bomb exploded near the Omar Bin al-Khattab mosque in the al-Hamra district of Homs.
The official news agency claimed that on the outskirts of Homs, the Syrian army killed scores of rebels in an offensive on their hideouts.
Meanwhile, the Observatory said the Syrian army had launched air strikes on the northern city of Aleppo.