The 15 year old was walking home from school along Surrey Road about 3.20pm on Wednesday when she was approached from behind by a man driving a vehicle.

As she walked along the footpath, the driver offered the girl a lift home and asked her to get in the car.

After asking her a second time, the girl pulled out her mobile phone from her bag and threatened to call police before the man drove off.

Detective Leading Senior Constable John Clark, of Ringwood crime investigation unit, said the driver had not committed an offence.

"It's certainly not an attempted abduction or child steal.

"It may have just been a sinister act, but it may very well have been an elderly man thinking he's doing the right thing in offering the girl a lift home. I don't know."

However, in light of recent attempted abductions in other parts of Melbourne, Detective Leading Senior Constable Clark urged children not to walk home alone and to be aware of their surroundings.

The principal of the girl's school, which the family requested not be named, said safety strategies had been discussed with students and the Department of Education made aware of the incident.

"We have increased vigilance among staff and are taking this very seriously," the principal said.

Information to Crime Stoppers on 1800 333 000 or www.crimestoppers.com.au