The cinema on the MA Jinnah road has been running housefull.
Police said they were investigating the motive behind the attack as the modus operandi of attackers was similar to those who use grenades to damage property and spread fear.
"Two men on a motorcycle threw the hand grenade at the entrance of Capri cinema and fled from the scene. Two persons were injured," senior police official Imran Shaukat said.
There is a heavy rush at all single screen cinema halls and the multiplexes and cineplexes in the city due to the Eid holidays.
In another incident, four people were injured when a bomb went off in a coaster in North Nazimabad area.