It allegedly happened near the arcades in the inside section of the park between 12.10 pm and 12.30 pm on Tuesday.
The States police have declined to reveal the nature of the incident for investigative purposes.
According to the force, the man, who was captured on grainy CCTV footage, is slim, of average height and about 40 years old.
He was wearing a grey polo shirt, grey shorts, black sunglasses and was clean shaven and had short dark hair.
Anyone with information is being asked to phone the States police on 612612 or Crimestoppers on 0800 555 111.
