A conductor was pushed and slapped by a passenger after he refused to let him on a tram for being too drunk.
The 28-year-old victim was assaulted at Cabin tram stop, North Shore, while a passenger attempted to intervene.
The offender then made off on foot, leaving the conductor with neck pains as a result of the attack.
He is described as white, around five ft eight ins tall, of stocky build with short black hair.
He was wearing a black top and black jeans.
Detectives are set to liaise with Blackpool Transport to obtain CCTV footage from the scene.
Anyone with information about the assault, which happened at around 6pm on Friday, should call 101.