They were walking along the footpath at the back of the park near the miniature railway when they came across a group of around 5-6 youths sat on a bench, with what looked like two pit-bull terrier dogs.
Both men sustained facial injuries in an unprovoked attack by members of the group, which required treatment at Southampton General Hospital. One was also bitten by one of the dogs.
Anyone who witnessed the incident or knows who is responsible is asked to contact Bitterne police station on 101 or anonymously on the Crimestoppers charity line 0800 555 111.