The fighting erupted after several groups of rebels attacked an artillery battery of the Syrian army, the ministry said. "During the fighting, which lasted for almost an hour, the military destroyed 43 terrorists and six all-terrain vehicles with large-caliber armaments installed on them", the ministry said.
The Syrian Observatory for Human Rights said the jihadists had targeted a group of Syrian and allied Russian fighters near the town of Mayadeen in Deir Ezzor province on Wednesday.
Russian servicemen and military facilities in Syria have been attacked by militants several times, causing a number of deaths.
The remaining 26 were all Syrian forces, he told AFP.
At least four Russian servicemen, including two military advisers, were killed in Syria after they were shelled by militants, the Russian Defense Ministry said Sunday.
It did not give a date or precise location, but the Observatory said it was the same incident as the IS attack near Mayadeen.
Two military advisers died on the spot, while two others succumbed to their wounds in a hospital, the statement added.
The Russian military assistance, which began in September 2015 at the official request of the Syrian government, has proved effective as Syrians continue to recapture key areas from Daesh and other terrorist groups across the country with the backing of Russian air cover.