Police said the 17-year-old was walking along Great Victoria Street near the junction with Ventry Street on Monday evening, when a car containing a number of men pulled up alongside him.
The men got out and then assaulted the victim knocking him to the ground.
Detectives believed the gang may have used a hammer may to attack him.
The gang left in the vehicle and the teenager was able to raise the alarm.
Police said he was taken to hospital, but his injuries were not thought to be serious.
Detectives have asked anyone who witnessed the attack or know who carried it out to contact them on the 101 non-emergency number at Musgrave PSNI station.