The Kermadec Ocean Sanctuary has been given the go-ahead by a Parliamentary select committee, but the Labour Party says Māori interests are still being overlooked.
The plans would see the area around the Kermadec Islands permanently converted into a marine life sanctuary, covering 620,000 square kilometres north-east of New Zealand.
Some fishing groups and iwi have opposed the proposal, which would ban all fishing in the area.
Labour's spokesperson for conservation Nanaia Mahuta said they felt like they had not been properly consulted.
"If they had consulted at the front-end and tried to find a solution with the co-operation and agreement of Māori fisheries interests, there could have been a solution, but we're not in that situation."
Environment Minister Nick Smith said the sanctuary was an important environmental commitment and would have the dual Kermadec/Rangitahua name.
"The government was keen to resolve outstanding iwi concerns through discussion," he said in a statement.
"We acknowledge the strong support for the sanctuary by Ngāti Kuri and Te Aupōuri but would prefer to have broader support from Māori for this globally significant initiative."
A Colmar Brunton poll conducted in May showed 86 percent of Māori supported the sanctuary.
The law, as recommended by the committee, includes the requirement for it to be reviewed after 25 years.
Ms Mahuta said 10 years would have been more appropriate.