"I recall my tupuna Te Wherowhero faced similar threats. He simply decided that the hole being dug for him would be filled by those with the shovels.
"I will continue to serve the Kingitanga movement to the best of my abilities. And I will continue to speak out fearlessly when necessary."
The Kīngitanga movement has been around for 160 years, and this koroneihana marked the 12th year since Kingi Tuheitia Potatau Te Wherowhero VII took over the mantle from his mother.
Tuheitia said he had instructed his advisers to begin "future proofing" the Kīngitanga for it to remain relevant for the next 160 years.
"I want to secure the stability of the Kīngitanga so that my family and my successors no longer have to face external, invasive and demeaning actions that diminish the mana of the Kīngitanga."
Tuheitia said he wished Prime Minister Jacinda Ardern well, as she managed the "challenges facing a new mother and continuing to provide leadership for her government".
"Prime Minister I urge you to continue to demand greater performance from your ministers and their departments; to ensure better outcomes for all citizens and in particular Māori."
The Herald has been reporting on the SFO issues for more than a year.
The SFO raided the office of the Māori King in July.
An earlier investigation into Ururangi Trust, responsible for funding the King's office, by the Charities Service branch of DIA had been ongoing since September 2017 but was brought to an abrupt end in June when Ururangi voluntarily deregistered itself.
Previous Herald reporting has raised concerns over whether Whakaruru used Ururangi's charitable funds to cover his $46,000 gastric band surgery at a private hospital in 2016, and also his company's use of low-interest related-party loans to cover $82,000 in non-charitable travel expenses.
Whakaruru has denied any misspending or wrongdoing at Ururangi.
At the time, Morgan welcomed the SFO investigation, and said he hoped it quickly got to the bottom of allegations.
In 2015 Ururangi was the subject of an adverse Charities Service investigation that warned further problems could see its charitable status revoked.
That report, obtained by the Herald last year, detailed the King's $350,000 annual salary and raised concerns about 114 transactions between 2012 and 2014 totalling $120,691, relating to the purchase of jewellery, clothing and beauty treatments and almost $90,000 in cash withdrawals.