The United States has no intention of stepping back from its involvement in the Asia-Pacific region, US Secretary of State Rex Tillerson has assured Prime Minister Bill English.

Mr Tillerson met with Mr English and Foreign Minister Gerry Brownlee at Premier House in Wellington.

During this meeting, they talked about New Zealand's training mission in Iraq and Mr English said he voiced New Zealand's disagreement with President Donald Trump's decision to leave the Paris Agreement.

Mr Tillerson defended Mr Trump's decision to pull out of the accord on climate change, saying it represented "the will of the American people".

He said the US was very proud of its "extraordinary record" of reducing greenhouse gas emissions, "possibly unparalleled by anyone else".

And he said there was no reason that would stop now.

"Our greenhouse gas emissions are at levels that were last seen in the 1990s. That's been done with 50 million more energy consumers than we had in the '90s with an economy that's twice as large.

"That's been done without a Paris climate accord. It's been done without heavy-handed regulation. It's been built on technology, innovation, entrepreneurship."

Mr Tillerson said the US intended to remain engaged on the issue of climate change on the world stage.

"I don't think anyone should interpret that the US has somehow stepped away from these issues or is seeking to isolate itself."

The US had "every intention" of directly engaging with the Asia-Pacific region on trade relationships; discussions with some countries were already under way, he said.

Photo: RNZ / Hans Weston

Mr Tillerson said the US viewed the region as "extremely important" for both security and economic reasons.

"One of reasons I'm in the region, one of the reason Vice President Pence has already been to the region, Secretary Mattis has been to the region, is to reaffirm to everyone that the United States views this region of the world as being extremely important to both our national security interest and our own economic and prosperity interests.

"You can expect, in fact, to see an elevated level of engagement to that that you saw in the past eight years."

Mr Tillerson was also asked about Mr Trump's tweets, including his response to the president's negative comments about the mayor of London after the weekend's terrorist attacks.

"The president has his own unique ways of communicating with the American people and the world - and it's served him pretty well.

"And I don't intend to advise him on how he ought to communicate, that's up to him."

Pōwhiri and protest

Mr Tillerson was greeted by a full pōwhiri at Premier House this afternoon, as about 200 people gathered outside Parliament to protest the Paris Agreement withdrawal.

It was the first top-level meeting between the New Zealand Prime Minister and the Trump administration.

New Zealand has a strong interest in what the US government has been doing with trade and climate change.

Mr Brownlee before the meeting that said the two countries shared a "deep interest" in maintaining peace, prosperity and stability in the Asia-Pacific region.

He welcomed the visit by Mr Tillerson - a former Exxon Mobil chief executive and chairman - as a chance to strengthen the relationship and discuss some of the world's "most pressing" issues.

As Energy Minister, Mr Brownlee met Mr Tillerson some years ago, while he was still at Exxon Mobil.

"I found him to be extremely knowledgeable about New Zealand and extremely respectful of the laws that we had ... and if that short experience is translated into the way he deals with other countries ... then I think there are grounds to be optimistic."

Labour leader Andrew Little said today's meeting was the "perfect opportunity" for the government to show some leadership and make some "forceful representations" to the US about its decision to withdraw from the Paris Agreement.

"To say this is not acceptable - the whole world needs to be in this and what the US has done has shown a retreat from leadership rather than doing something positive."