Tonga has been hit by four metre waves which have caused damage but no casualties have been reported.
As the tsunami makes its way through the Pacific, the Government is likely to send an Orion to Samoa to help search for survivors and assess damage.
The Government and Defence Force were waiting to see how the tsunami affected other Pacific nations, a spokesman for Foreign Affairs Minister Murray McCully said.
The minister's office had received reports of five people dead in Samoa and "many more washed out to sea" following the tsunami there this morning, he said.
Tonga was now reporting tidal surges on some islands.
People had moved to higher ground and no casualties had been reported despite the "significant" waves, the spokesman said.
Samoa was hit with 6-8 metre waves on the south coast earlier today.
Seventy-six New Zealanders were registered with the Ministry of Foreign Affairs and Trade as being in Samoa but there were likely to be many more school holiday travellers, the spokesman said.
There were "bigger than usual" waves in the Cook Islands, with swells up to 1m being reported in Rarotonga.
In Tokelau, which comprises three low-lying atolls, people remained on alert and were taking precautions and moving to higher ground.
No high waves had been seen but people were waiting to see what would come.
Niue was reasonably safe because it was high and the concern there was for people out on the water, the spokesman said.
"Reasonable" sized waves had been seen and the earthquake that sparked the tsunami was felt there.
In Suva, Fiji there were reports of waves hitting around 10am local time but no damage was reported.
Neither Vanuatu, Kiribati, New Caledonia nor the Solomon Islands had reported high waves.
The New Zealand Government had held major concerns for the tiny low-lying Pacific states of Tokelau and Tuvalu, but a spokesman for Foreign Affairs Minister Murray McCully said reports from both countries confirmed they had not been hit by a tsunami.
It appeared they had escaped damage as they are to the north of Samoa and the earthquake was to the south of Samoa.