A Waikato River iwi says Landcorp's conversion of forestry to dairy farms in its rohe goes against the purpose of its Treaty Settlement.
The state-owned enterprise plans to add more than 29,000 cows to upper Waikato farms it is converting from forestry.
The Green Party wants it to stop, saying the effluent from the cows will pollute the Waikato River.
Ngāti Koroki Kahukura spokesperson Linda Te Aho agreed, and said the plans did not align with the Māori world view.
She said Waikato iwi had secured a Treaty settlement to restore and protect the health and wellbeing of the Waikato River for future generations.
But she believed the Crown action went directly against the overarching purpose of the settlement.
Ms Te Aho said the Crown should be showing leadership in doing more to combat climate change.
The Green Party said 8,000 people have signed a petition calling for a moratorium on Landcorp's conversions.
It will present the petition to the Primary Production select committee on Thursday.