The 15-year-old victim was walking along Firle Road, near the junction with Havelock Road, around 7pm on Friday, October 2 when she was approached by an unknown man.
He pushed the girl against a wall but fled the scene when she fought back. The victim suffered a minor injury to her hand.
The suspect is described as around 25 years of age, with short brown hair. He had a baseball cap on backwards and was wearing a hooded jumper.
Anyone who saw what happened, or who witnessed any suspicious behaviour in the area at the time, is asked to contact police online or by calling 101 quoting serial 902 of 06/10.
Alternatively witnesses can contact the independent charity Crimestoppers anonymously on 0800 555 111.