The woman was walking alone along Franklin Road at around 3.30am when she heard footsteps close behind her. A man passed her and then further up the road he jumped out from behind a parked car and threw her to the ground.
The victim managed to fight him off and he ran away in the direction of the town centre.
The woman was not injured in the attack but was understandably left shaken.
The attacker is described as a white man in his mid-20s, between 5ft 8ins and 5ft 10ins tall and of slim build. He was wearing a blue hoodie with the hood pulled up and tightened round his face.
Police are stepping up patrols in the area and are appealing for witnesses or anyone with CCTV coverage of the area to get in touch.
Anyone with information that could help the investigation is asked to call 101 and quote reference number 12190142213.
If you wish to remain anonymous you can contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.gov