The vehicle was traveling from the town of Dragas to the Serbian capital Belgrade with 57 passengers on board.
A bus traveling between Kosovo and the rest of Serbia was also attacked late last year, with no injuries.
The UN has administered Kosovo since June 1999 when NATO air strikes chased Serbian forces from the province.
The majority ethnic-Albanian population is seeking independence for the province, while Belgrade says it must remain part of Serbia.
(AFP/Reuters)