The 35-year-old victim suffered a fractured jaw and cheekbone in the attack, which happened around 1.30am, and was taken to the Edinburgh Royal Infirmary for treatment. He remains in hospital in a stable condition.
A Lothian and Borders Police spokesman said:
We want to speak to anyone who was in the area of the High Street in Prestonpans in the early hours of this morning, who may have witnessed the incident or saw or heard anything suspicious.
Anyone else who has any information that can assist our inquiries should also get in touch.
Anyone with any information can contact: