Huawei has been involved in other telecommunications systems in New Zealand such as its 4G mobile network, and is investing NZ$400 million ($271.88 million) into research and development.
Little said each decision regarding telecom technology was made separately under telecom and security legislation.
"The difference between 5G networks and conventional 4G and 3G networks is the configuration of the technology," Little said. "With 5G technology, every component of the 5G network means every part of the network can be accessed."
That echoed Australian concerns that, with 5G, it was difficult to confine vendors considered high risk to a network's less sensitive parts.
Spark rival 2degrees said it had noted the decision and was "seeking clarity on it".
"The importance of multiple vendors to deliver price competitiveness still stands, so if this announcement has a similar impact on 2degrees it will be a real disappointment for competition," 2degrees corporate affairs chief Mathew Bolland told Reuters.
Vodafone New Zealand Ltd declined to comment on the matter.
