Police are looking for two men who allegedly tried to push a teenager into a fountain before then punching him in the face.
It happened on Broad Street sometime between 1:20am and 1:50am on Saturday 3 July.
Police have no description of the men.
The boy, thought to be 17 years old, didn't need medical treatment.
Another boy and two girls of a similar age were standing by the fountain at the time.
Anyone with information on what happened is asked to call police on 612612 or Crimestoppers anonymously on 0800 555 111.

Ferry hits berth in St Helier harbour
Help stitch a Jersey Bayeux tapesty
Fire at former Jersey hotel
One year of DFDS' Jersey contract
Prosecution for 'Jersey Lifts' drivers agreed by politicians
States back measures to protect cash use in Jersey
New interactive map charts shipwrecks and dolphin activity
Survey reveals scale of dissatisfaction with off-island travel