Police are appealing for witnesses after the attack on the 21-year-old, who was walking up the stairs between Guthrie Street and Chambers Street at 1:10am on Monday. He heard someone shouting at him and turned to find a man threatening him and demanding cash.
He began to run up the stairs but a second man appeared at the top, rugby tackled him and began assaulting him.
The victim managed to fight off his attackers and they fled without taking anything
Detective Constable Gavin Watson said: "This seems to be totally opportunistic. He fought back and the two suspects made off, which is not necessarily something we would always advise doing, but fortunately there were no serious injuries, although he has been shaken by the incident."
Both suspects were white, and around 16 or 17 years old. The first was 5ft 7ins tall with a thin build, wearing a silver or grey Adidas tracksuit top, jogging bottoms and trainers. The second had a thin build, and was wearing a red short-sleeved shirt. Anyone with information should contact police on 0131-311 3131, or Crimestoppers on 0800-555 111.