Police have released images of a man they want to question after the incident on Monday in Portsmouth, Hampshire.
The suspect is described as being a black man of slim build aged between 18 and 25, with dark hair.
He approached the youngster and made sexual comments before touching her inappropriately, police say.
A Hampshire Police statement reads: "We have been conducting enquiries since this incident was reported to us and now have these images of a man, seen in the area at the time, who we would like to speak to in connection with our investigation."
Hampshire Police released images of the suspect
Hampshire Police
He is described as:
- Aged between 18 and 25-years-old
- Black
- Of slim build
- Black hair
- Dressed all in black, apart from a white t-shirt with a black vest over the top of it. He was also carrying a small black bag.
The girl managed to get away from the man. He followed her for a short distance but left once she reached Rudmore roundabout and called police.
She is currently being supported by specialist officers.
Anyone with any information that may assist our enquiries, no matter how small it may seem, is asked to call us on 101 quoting 44220351818.
Alternatively, go online and submit information.