The Pacific Tsunami Warning Center said hazardous waves were possible in New Zealand, Tonga, Niue, American Samoa, Samoa, the Cook Islands, Fiji, Vanuatu, Tokelau, and Wallis and Fortuna.
The quake followed a large earthquake that struck just four hours earlier and was felt by tens of thousands, causing its own tsunami warning. This warning was later lifted.
"Hope everyone is ok out there - especially on the East Coast who would have felt the full force of that earthquake," Prime Minister Jacinda Ardern posted on Instagram after the first quake.
There was threat to the capital Wellington and other regions from the initial tremor, but civil defence authorities asked residents across the country to stay away from beaches and marine areas as there could be strong and unusual currents.
More than 60,000 people reported feeling the quake on GeoNet's website, with 282 describing the shaking as "severe" and 75 saying it was "extreme". Most others described it as light.
"Strong and unusual currents and unpredictable surges near the shore are expected in all other coastal areas of the North Island, Great Barrier Island, the South Island, Stewart Island and the Chatham Islands," a statement on the GeoNet site said.
Aftershocks were still being recorded in the area.
Tens of thousands of coastal residents in New Zealand, New Caledonia and Vanuatu fled for higher ground on Friday as a series of powerful earthquakes sparked a Pacific-wide tsunami alert.
Warning sirens sounded as authorities ordered evacuations amid fears of waves of up three metres (10 feet).
"People must leave beach areas and stop all water activities, and should not pick their children up at schools to avoid creating traffic jams," emergency services spokesman Alexandre Rosignol told public radio in New Caledonia.
In New Zealand, communities along stretches of the North Island were warned to flee as tsunami alert sirens wailed after an 8.1-magnitude earthquake, which followed earlier tremors in the same region measuring 7.4 and 7.3.
"Do not stay at home,"the National Emergency Management Agency (NEMA) said.
"People near the coast... must move immediately to the nearest high ground, out of all tsunami evacuation zones, or as far inland as possible."