The nine-year-old was playing with friends at Tunstall Square Shopping Centre in Doncaster East when he was approached by a man about 12.15pm on Saturday.

The man asked the boy if he liked cars before grabbing his arm, police say.

The boy was able to break free and ran to his mum, who was nearby.

Jessica Rocker said she was at the busy shopping complex with her two children on the day of the AFL Grand Final.

"I don't understand anyone who would do something like that to a kid," the boy's mum told Nine News on Monday.

Police on Monday release a computer-generated image of the man, who they want to speak to over the incident.

They said the boy had provided a clear description of his would-be attacker, helping their investigation.

He had a tattoo of a snake around his neck and a profane word tattooed on his left hand.

Police also want anyone at the shopping centre at the time who may have dash cam footage of the incident to contact them.

Australian Associated Press