The incident happened at around 01:00 on Sunday inside Folies nightclub, with Guernsey Police saying one man received injuries to his head, thought to be caused by a glass being thrown.
Police would like to speak to anyone that may have witnessed it.
Anyone with information is asked to contact PC 97 Du Port on 725111 or through Crimestoppers on 0800 555 111.
Pictured top: Folies D’amour nightclub.