The incident happened at around 7.30pm on Saturday outside the Indian restaurant Killermont Polo Club in Maryhill Road, Glasgow.
Five or six men approached the 22-year-old victim as he waited at the bus stop, before attacking him and inflicting serious facial injuries.
They then fled on foot along Maryhill Road in the direction of Maryhill railway station.
The victim was taken to the Glasgow Royal Infirmary and treated.
Detective Constable Katy Allan, Maryhill Police Office, said: “This man has sustained serious injuries and our officers are doing everything they can to trace those responsible.
“Violence will not be tolerated.”
She added: “We know that there were a lot of cars passing by at the time of the incident, particularly a black Range Rover that was turning into the Killermont Polo Club at the time of the attack.
“We are asking you to think back, do you remember seeing anything? You may not have realised how serious it was at the time. We urge you to get in touch.”
The suspects are described as a group of five or six white men in their late teens or early 20s.
One of the men is described as being 17 to 20, of heavy build with short brown hair.
He was wearing a dark tracksuit.