The Prime Minister has written to the United States president seeking an exemption from his steel and aluminium tariffs.
Donald Trump signed off earlier this month on tariffs of 25 percent on steel imports and 10 percent on aluminium imports, but exempted some countries, including Canada, Mexico and Australia.
Jacinda Ardern said she outlined in the letter her understanding of his concerns and what drove the imposition of the tariffs.
"We are awaiting a response, as are many other countries who have sought an exemption as well."
Finance Minister Grant Robertson earlier said he did not support the tariff and did not want a trade war.
The tariffs are expected to come in on 23 March.