The 30-year-old was walking on Govanhill Street, Glasgow, at about 8am when he was approached by three men.
After telling them he did not have any cigarettes, the men followed him and assaulted him on Kingarth Street.
The victim was treated for an injury to his head at Victoria Infirmary.
Police have released descriptions of the three men who carried out the unprovoked attack.
They are white, aged between 17 to 20, and one has dark brown hair, wore a blue hooded top and has a scar on his face.
The second also has brown hair and was wearing a light-coloured top. The third suspect has red hair.
Detective Constable Mark Hendry said: "We are currently reviewing all CCTV and carrying out extensive inquiries to trace those responsible for this unprovoked attack.
"I am appealing to anyone who was in the area around Govanhill Street, Kingarth Street and Inglefield Street on Sunday morning and saw or heard anything that might help progress the inquiry to come forward."
Anyone with information is asked to call Police Scotland on 101 or Crimestoppers on 0800 555 111.