A nail bomb and a blast bomb has been thrown at police during disturbances on the flashpoint Ardoyne Road.
A police spokeswoman says large crowds are gathering in the area.
Two police officers were slightly injured by the two devices.
The violence follows the death of a Protestant teenager in a hit-and-run incident.
The RUC said the death of 16-year-old Thomas McDonald is being treated as murder.
He was hit by a car which mounted a footpath in the city's Whitewell area, where rival crowds stoned and petrol bombed each other just hours earlier.
It happened three miles from the Holy Cross Catholic Primary School, where Protestant protesters have tried to block Catholic children from walking to school.
The death provoked threats of more serious disturbances. A family friend of the dead boy said: "It will be an eye for an eye."
Police later arrested a 32-year-old woman and were questioning three others in connection with the incident.
It is understood the car involved, a silver Ford Focus, followed the teenager into White City after a stone was thrown at the vehicle as it emerged from the nearby nationalist Longlands estate.