The assault, which was described by police as a "sustained and violent attack", took place at around 10pm on Friday night in the Langlee area of the town.
The man the police want to question is described as white, 5ft 7in and skinny, with dirty-blonde hair.
He has a tattoo on the back of his neck, a burn mark on his right forearm and a cut on his right index finger, which was bleeding.
The man was also wearing blue jeans with a red belt, and a blue top with vertical stripes.
Police are urging the public to help them find the man.