Far North Mayor Wayne Brown says he has no confidence the Coastal and Marine Area Act will protect public access to beaches.
Two Maori iwi have formally expressed interest in seeking customary title under new seabed and foreshore legislation enacted in March this year.
The Marine and Coastal Area Act allows the tribes to seek title to areas where they can prove uninterrupted and exclusive occupation since 1840.
The iwi are Kaitaia-based Te Rarawa in the Far North and Ngati Pahauwera on the East Coast.
Te Rarawa has confirmed it will seek customary title to Te Oneroa a Tohe, or Ninety Mile Beach.
Mr Brown says he has already been ordered off beaches in the region by angry young Maori men and chose to leave rather than risk a fight.
On two occasions, Mr Brown says he has come into a beach from his boat with his wife and been confronted while walking below the high-tide mark.
A spokesperson for Te Rarawa, Haami Piripi, says encounters such as Mr Brown's stem from resentment and uncertainty.
Mr Piripi says tangata whenua (people of the land) are uncertain of their rights and aggrieved at the lack of recognition for them.