A claim by an eight-year-old girl that she was attacked by a man at a Melbourne primary school was "false", police said on Tuesday.

Last week, an officer said the girl had been approached by a man in the grounds of Glenferrie Primary School on Manningtree Road in Hawthorn about 3:30pm (AEST).

The man dragged the girl into a secluded area where he physically and verbally attacked her before undoing her uniform top, Detective Senior Constable Alexia Bieser said.

Describing the reported attack as "disgraceful", Detective Senior Constable Bieser said the girl had suffered minor injuries.

"[The attacker] was angry and growling and swearing at her," she said.

Police released a computer-generated image, called a comfit, of the man said to have attacked the girl.

The school had since upgraded its security and students were given supplementary age-appropriate stranger danger training.

A community policing meeting was held following the reported attack.

On Tuesday, detectives from the Box Hill Sexual Offences and Child Abuse Investigation Team said an investigation had found that no attack took place.

"Enquiries have revealed the information that was reported to police was false and that the incident did not occur," a statement said.