Residents on the east coast and in Auckland have been warned to stay away from the beach with a tidal surge of up to one metre possible in some places.
Civil Defence national controller David Coetzee said there had already been some wave activity in Northland in the 10s of cm and the public safety message is still to stay out of the water because of the trickle effect further south of Hawkes Bay.
He said for anyone who does go into the water, "you might find you will be smashed around and it may be life-threatening".
A tsunami warning issued for New Zealand following a 7.6 magnitude earthquake off the Kermadec Islands was cancelled around 8.30am today.
But Civil Defence says there was still a marine threat posing a risk to boats. Mr Coetzee said a first wave will not necessarily be the biggest.
The tidal surge was expected to strike New Zealand at these times:
East Cape at 8.52am
Northland at 8.54am
Gisborne at 8.59am
Auckland's east coast at 10am
Mr Coetzee said a strong current current was likely with unpredictable turbulence in the water.
"My advice is to stay out of the water all day."
When asked if we people could go and watch the tidal surge, he responded "why would you want to do that, get on with your life."
A Department of Conservation spokesman told Newstalk ZB there were eight DOC staff on Raoul Island near the epicentre, who felt a jolt but no one was hurt and nothing was damage.
Large quake rocks Kermadec Islands
The Pacific Tsunami Warning Centre earlier issued a warning for New Zealand, Tonga and the Kermadec Islands.
The United States Geological Survey reported the quake struck at 7.03am at a depth of 20km, and was centred 211km east of Raoul Island.
The Kermadec Islands are a island chain 800km north of New Zealand.
View Earthquake in the Pacific in a larger map