The Maori Party says the Government should consider negotiating with not only individual iwi, but the group being formed following a national hui on water rights.
More than 1000 people attended the hui at Turangawaewae Marae in Ngaruawahia on Thursday, called by the Maori King, Tuheitia.
The hui was prompted by the Government's decision to speak to selected iwi separately ahead of its partial sale of state-owned Mighty River Power.
Those attending the hui resolved that, should all else fail, iwi would support court action taken by the Maori Council and voted to stand united and form a group to represent all Maori in negotiations with the Crown.
But the Government said on Friday the resolutions make no difference to the way it intends to negotiate with Maori. It acknowledged Maori interests and rights in water, but still believes the best way to approach that is iwi by iwi.
But Maori Party MP Te Ururoa Flavell said on Friday his party believes the Government should consider talking with the group also.
"They've got to find a place for both sides - have the national debate and negotiate with a body that clearly has been set up from the hui called by Kingi Tuheitia.
"But also, there are claimant groups that have a part to play - and that needs to fit within a bigger picture."
Mr Flavell said it is not the first preference of Maori to take the Crown to court over water rights - but if it comes to it, iwi will back that course of action.
"It's clear from the hui that our people view going to court is in no one's interest, but it has to be there to protect the position. There's a reluctance I think to go to court - but if it's going to be there, then clearly the picture is that all iwi will come in behind that action."
Greens co-leader Metiria Turei says Maori now have greater leverage and the Government should not ignore the mandated group.
"It would be very difficult for (Prime Minister) John Key to meet with the negotiators chosen by Maori. The resolutions from the hui were very clear that they want to take a collective approach - I don't know that John Key can refuse them on that basis."
The Labour Party says potential court action creates yet another hurdle for the Government's asset sales programme.