It happened Saturday night at about 9:30 on a northbound A train as it approached Columbus Circle.
Two teens, a 16-year-old girl and a 16-year-old boy, were taken into custody in connection to the attack and face possible assault charges.
The attack appears to have been sparked by the victim soliciting for money, investigators said.
The 29-year-old victim was taken to the hospital. Police say he suffered minor facial injuries.