The singer/songwriter Gavin DeGraw was attacked by a group of "unknown males" in the early hours of Sunday morning and suffered a broken nose and a cut to his face.
Despite being wounded, he kept walking and ended on 19th Street and 1st Avenue in the city, where he was struck by a cab, although his injuries from the accident were not serious.
He was then taken to the nearby Bellevue Hospital in an ambulance and is still under observation.
A source said: "He was attacked but it was not his fault."
His spokesman added there would be "no additional information".
DeGraw is scheduled to perform tonight in Saratoga Springs, New York, with Maroon 5 and Train but it is not clear whether he will be able to take to the stage.
A source said yesterday: "They don't know yet if he will be OK to make the show tomorrow."
An investigation into the assault is ongoing.
The 34-year-old star has a new album, 'Sweeter', out in September and he is probably best-known for his hot song 'Chariot'.