The fight, which happened at around 02:00, spilled out into the road, with at least one person reported as injured.
Guernsey Police is looking to talk to anyone who may have seen what happened. Alternatively, if any business has CCTV of the incident, they are being asked to come forward.
If you have any information please contact the police on 725111 or Crimestoppers anonymously on 0800 555 111.
Pictured top: the incident happened in the entrance to Da Nello’s and then spilled out onto the street.