The Far North District Council is accused of bypassing iwi in a vote on creating Māori wards.
Locals have rejected the option, with two thirds of respondents saying no to dedicated seats.
Post-settlement group Te Runanga Nui o Te Aupōuri said there was poor promotion of the poll and few Māori knew about the ballot.
Its secretary, Peter-Lucas Jones, said the council failed to take advantage of the tribal networks to spread the word about the poll.
"They've kind of bypassed iwi with this process that gives initiated and completed," said Mr Jones.
"In hindsight, I believe that this could've been communicated more clearly through working with iwi around opportunity to tribes and how to raise awareness of voting".
Far North Mayor John Carter accepted the criticism.
"Well, see, that's the sort of thing that we need to have better liaison and discussion", said Mr Carter.
"It really opens up the opportunity for us to make sure that if there are gaps that we close them.
"And so that's a classic example whereby that is an area that we need to do more work on."