Police are looking to speak to any witnesses to the alleged assault, which happened shortly after 1 pm.
The man is described as 6 feet 2 in, skinny with white hair and is thought to be between 60 and 70 years old.
He allegedly approached the woman from behind and touched her inappropriately before leaving the area.
Anyone with any information about the alleged assault can contact the police on 612612 or call Crime Stoppers on 0800 555111.
