A woman has been sexually assaulted on a Richmond tram, while several other passengers were on board.

The 38-year-old Forest Hill woman was travelling along Bridge Road about 10pm on Valentine's Day when she was assaulted by a male passenger.

The computer-generated image of the man wanted over a sexual assault. Credit:Victoria Police

The man approached the woman and sexually assaulted her while several other passengers were on the train, police said.

After the assault, the man got off the tram near the intersection of Bridge Road and Lennox Street and walked north towards Cameron Street.

The tram was on route 75, travelling towards Vermont South.

Investigators have released a computer-generated image of a man they wish to speak to.

Anyone with information about the incident or the man's identity is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au.