A man was seen to verbally abuse and physically assault a woman in West Street, at the junction with Russell Road, around 11:30pm on Sunday 11 July.
He is described as black, wearing dark clothing, a grey jacket, black trousers and black shoes.
The woman was white, with long blonde hair, wearing a white jacket and white shorts.
Police are urging the victim to come forward to ensure her welfare, and are keen for anyone who saw what happened – or anyone with camera phone footage – to get in touch.
You can report it online or call 101, quoting serial 1500 of 11/07.