A 26-year-old man was sitting on his own on a bench in Wednesday Market, when he noticed a man, who was not known to him, sitting inside the nearby Casa Bar.
As the man left the Fusion Tapas Bar the two of them became engaged in a verbal altercation which resulted in the 26-year-old man being assaulted.
Following the assault the offender walked away and was followed by the victim who tried to engage with the man in order to establish why he had been assaulted. It is then alleged the man assaulted him again before running away.
The victim sustained a suspected broken jaw as a result of the assault.
The offender is described as a white man, 6ft tall and of a medium build with ginger hair.
Anyone who may have information in connection with the incident is asked to call Humberside Police on the non emergency number 101 quoting crime number 1927062.