Dandenong Sexual Offences and Child Abuse Investigation Team detectives are appealing for information following two incidents on the same bus line last week, Victoria Police say.
Investigators have been told a 17-year-old girl was on board the 893 bus from Cranbourne to Dandenong about 6pm.
She exited the bus at Waverley Park Drive, Cranbourne North where a man had been waiting at the stop.
He started following the victim before grabbing her and kissing her.
The victim fought back and the man verbally abused her before producing a knife and punching her.
She sustained minor scratches and the man fled.
About 2.30pm the following day, a 17-year-old girl was waiting with friends at a bus stop on the Princes Highway near Harmer Road, Hallam waiting for the 2.38pm bus.
A man crossed from the other side of the road towards the bus stop and began shouting abuse at the victim and her friends.
He grabbed the victim and pushed her into a bus stop before abruptly leaving.
She sustained minor bruising during the incident.
The man was seen walking along the Princes Highway and turning left onto Harmer Road.
Detectives believe the same person was involved in both incidents and have released a composite image of a man who they believe can assist with their enquiries.
He is perceived as Caucasian in appearance, about 40 to 50 years old and unshaven.
The man wore black pants, a grey top and black cap during the second incident and was carrying a black backpack.
Police are also hoping to speak to a woman with a pram, who came to the aid of the first victim at the time.
Anyone with information is urged to contact Crime Stoppers.
