The 37-year-old suffered a head injury after being assaulted by three men on bikes in the Newbigging area of the town on Sunday night.
The victim had left a licensed premises on the East Lothian town’s High Street at around 9:45pm when he was confronted by the men and struck on the head with a glass bottle, causing him to fall to the ground.
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A member of the public came to the man’s aid and contacted emergency services shortly after the suspects fled the scene.
He was taken to the Royal Infirmary of Edinburgh for treatment before later being released.
Police have since launched an appeal for information.
One of the men was described as wearing light grey jogging bottoms and a darker hooded top, while another was wearing all dark clothing.
The third was said to be wearing light grey jogging bottoms, a lighter coloured hooded top and a body warmer.
All three were riding bicycles.
Detective Constable Kenny McKenzie from Lothian and Scottish Borders CID said: “This appears to have been an unprovoked attack, which left the victim with a painful injury to his head.
“We would request that members of the public who were in the Newbigging area during Sunday evening and witnessed this attack, or saw anything suspicious, contact police immediately.
“In addition, anyone who can help us trace the suspects should also get in touch.”
Those with information can contact Lothians and Scottish Borders CID via 101 and quote incident number 3636 of the 13th January. Alternatively an anonymous report can be made to the charity Crimestoppers on 0800 555 111.