Detective Inspector William McDicken, from Saltcoats CID, said: "Understandably, this young girl has been left very upset following her ordeal.
"We are continuing extensive enquiries, including reviewing all available CCTV in and around the area of Glasgow Street and we have been carrying out door-to-door enquiries.
"I would like to appeal to anyone who was in the vicinity of Glasgow Street at the time of the incident, particularly to those making their way home from a night-out, did you see this young girl walking on Glasgow Street? Did you see a man fitting the description of the suspect? You may have information that could help with our enquiries."
Anyone with information is asked to contact officers on 01294 404500 or Crimestoppers in confidence on 0800 555 111.