Two people have been arrested after a brawl broke out on Melbourne's St Kilda beach.

A large number of youths gathered in St Kilda on Saturday night and a fight broke out along the foreshore shortly after 10.30pm, police said on Sunday.

A male was injured but declined treatment at the scene.

Police also responded to reports of a robbery and assault in the area.

A 24-year-old man and a 26-year-old man were taken to hospital with non-life threatening injuries, while a 20-year-old man sustained minor injuries.

One person was arrested nearby on suspicion of possessing a prohibited weapon and another for making threats to inflict serious injury, with capsicum spray used during their arrests.