Police say the injured man, who sustained a broken jaw and broken nose in the attack, believes there was a sectarian motivation to the incident which occurred in Foyle Street, Derry at about 2.30 am on Saturday last.
The victim was walking towards Foyle Street car park after a night out with a friend when they were approached a group of up to 10 males and an argument ensued.
The man and his friend were chased to the car park and punched.
The injured man also suffered other facial and mouth injuries.
A PSNI spokesperson asked with information to contact police on the 101 non-emergency number.
Information can also be given anonymously to Crimestoppers on 0800 555 111.