Ngati Kahungunu is accusing the Government of bowing down to big business by changing legislation about foreign charter vessels, which it says is reducing tribal fishing quota by up to $100 million.
The tribe is supporting an earlier call by the Maori Party's Chris McKenzie, who said iwi should be compensated as a result of the amendments.
Both Mr McKenzie and the iwi support the Government's amendments which ensure foreign crews are not mistreated or underpaid.
But Ngati Kahungunu chair Ngahiwi Tomoana, suggested the Government had used that as an excuse for businesses to cash in. He said if the changes applied to all cargo ships, none of them would enter New Zealand waters because of the huge costs to de-register and re-register a ship here.
Mr Tomoana said established businesses were all right because they already owned their vessels, but iwi were not at that point yet.
He said from the settlement of all iwi, they got most of their money from deep sea fishing and from crayfish.
Mr Tomoana said its Maori industry was worth up to $400 million, and had already fallen by $50 million - $100 million per year.
In response, the Ministry of Primary Industries said the measures were not about bowing down.
It suggested they put more pressure on fisheries companies to meet new requirements.
The ministry said the law had wide support in Parliament and passed unanimously.
Minister Nathan Guy said it was serious about protecting the welfare of fishing crews and the country's reputation.
He said a select committee proposed an exemption to reflagging for certain vessel operators which were entitled to settlement quota.
Mr Guy said he carefully considered the proposals but exemptions risked undermining the Government's ability to enforce its labour and vessel safety standards on foreign charter vessels.
Fisheries company Sanford was unavailable to comment while Sealord declined to speak on the matter.
All ships will be required to reflag to New Zealand by 1 May 2016.