The man police believe may be able to assist with their investigation.

An image of the man being sought by police.

A young woman has managed to flee from a man who acted indecently and tried to grab her in a La Trobe University car park.

Police said the 21-year-old woman parked her car at the south entrance to La Trobe University's Plenty Road campus in Bundoora when she was approached from behind by a man about 11.25am on Tuesday, March 4.

The man started walking behind her with his hands down his pants.

Police have been told the man made suggestive comments to the woman and attempted to grab her backpack.

The man was sweating during the incident and mumbling to himself.

She ran away and sought help from a passer-by.

He is Caucasian, aged between 30 and 40, of solid build, approximately 175 centimetres tall, with shoulder-length brown hair in a ponytail, police said.

He was unshaven and had tattoos on the lower part of his right leg. He was wearing a dark blue singlet top and sand-coloured shorts, police said.

Anyone with information is asked to phone Crime Stoppers on 1800 333 000.