The assault is said to have happened across the road from the Pomme d'Or hotel, next to the zebra crossing by Liberty Wharf, at around 10:20pm on Monday 24 July.
Officers received a report of a man being attacked, and are looking to speak to him.
He was described as white with short brown hair, and wearing a dark T-shirt with writing on the front, dark shorts and dark trainers.
Anyone with information is asked to contact Jersey Police on 01534 612612 or Crimestoppers on 0800 555 111.
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