The quake hit at 7.03am at a depth of 48km, 1,300km north of Wellington.
The Pacific Tsunami Warning Centre issued a tsunami watch for New Zealand’s East Coast, Northland, Bay of Plenty and Hawkes Bay.
The Centre had previously issued a warning but cancelled it, saying that only national and local government agencies have the authority to make decisions about the official state of alert in their areas. The Centre is located in Honolulu.
Civil Defence National Controller David Coetzee says it was their responsibility to do a local assessment.
He says the official tsunami warning status for New Zealand will be issued and updated after Civil Defence has carried out further assessment.
"The official status is that we are still under a warning situation," says Mr Coetzee.
The Warning Centre said that a wave had been generated, and was projected to reach the North Cape at 8.52am.
The wave was estimated to be around one metre high, but the Centre said that larger waves could follow. The waves will continue for several hours.
The warning has been issued for the whole of New Zealand, but the areas Mr Coetzee says are "more exposed in this instance" are the North Cape and the East Coast down to around Hawkes Bay.
“"The warning is really what we refer to as a marine threat,” says Mr Coetzee.
The Warning Centre and Civil Defence are advising people in coastal areas to stay off beaches, stay out of the water, and to follow the instructions of local Civil Defence authorities.