The incident took place at around 2 am on Sunday.
A middle-aged woman was approached and assaulted by a man, and police have issued a full description.
They say that the attacker is in his mid to late 20s, of Mediterranean appearance and around six feet tall with collar-length wavy brown hair.
He has brown eyes and was clean-shaven – at the time of the assault he was wearing a buttoned-up shirt.
Police say that anyone with any information should get in touch with them on 612612, or through the anonymous Crimestoppers number 0800 555111.