The device was thrown at a PSNI vehicle on the Oldpark Road, close to its junction with Rosapenna Street, on Wednesday night.
It is understood it struck the landrover but did not explode.
Army bomb squad officers later confirmed the device was viable. Dissident republicans have been blamed for the incident, in which no-one was hurt.
PSNI Superintendent George Clarke said: "We are extremely fortunate.
"This is absolutely and clearly an attempt to murder police officers.
"It not only shows a willingness and determination to kill people who are serving the community but it also shows complete disregard for the people living in that area.
"These devices are designed, intended and capable of killing."
The investigation is at an early stage but we think it's fair to assume this is the work of dissident republican terrorists.
Superintendent George Clarke
A security alert was sparked at around 10pm after a telephone bomb warning was made.
More than 20 local homes were evacuated while the army carried out tests on the device.
This incident comes after a pipe bomb was left at the Greater Whitewell Community Surgery on Tuesday night, while a group of teenagers were in the centre.
Staff told UTV the dissident grouping Óglaigh na hÉireann claimed responsibility in a warning call.
North Belfast DUP MP Nigel Dodds said: "Once again these terrorists have shown their total disregard for human life. They carried out this reckless attack within a residential area, having no concern that it could cause serious injury or death for PSNI officers or for any member of the public who passed this viable device as it lay at the side of the road.
"Only by good fortune this device did not explode.
"Once again the entire community is indebted to the bravery and expertise of our security forces in making this device safe."
SDLP councillor Nichola Mallon said the attack happened in a built-up residential area.
"I was at a well-attended meeting in Sacred Heart Parochial Hall last night with Fibromyalgia suffers just yards from where this pipe bomb was thrown.
"A number of people at this meeting were leaving the hall minutes before this happened and there was visibly a number of young people walking out and about," she said.
Sinn Féin councillor Danny Lavery condemned those responsible for "driving residents from their homes on a winter's night".
He said: "For the second time in a week the north Belfast community have been disrupted by a pipe bomb endangering people's lives. Those involved are idiots.
"Exactly who in this community supports these actions? Certainly not the dozens of elderly residents and young children put out of their homes last night."
Anyone with more information on the incident has been asked to come forward.