The device was thrown at a vehicle parked outside the offices of Groundwork Northern Ireland at Duncairn Gardens around 11 am this morning.
The 27-year-old suspect was arrested and questioned. He has now been released pending further inquiries.
There was no-one inside the car at the time of the attack.
Fortunately, the device did not explode on impact.
A number of people had to moved from their homes and Duncairn Gardens Community Centre was made available as a safe shelter
Businesses and a doctor’s surgery were also evacuated.
Army technical officers attend the scene and made it safe.
Duncairn Gardens was closed to traffic between Edlingham Street and North Queen Street during the security alert.