Hemati came off the bench in the 81st minute and was on target nine minutes later with a long-range shot.
Persepolis remained at second place of Iran Professional League (IPL) with 15 points, one point behind Padideh who was held to a goalless draw against Tractor Sazi in Mashhad.
It was a morale-boosting win for Persepolis ahead of Thursday's league game against arch-rival Esteghlal, who played out a goalless draw against Nassaji in Ghaemshahr on Saturday.