The ITF's decision follows Nastase's behaviour before and during Romania's Fed Cup tie with Great Britain in April.
At a pre-event press confernece, the Romanian captain made what the ITF described as a "highly inappropriate and racially insensitive" comment about Serena Williams' unborn baby - he said the child's colour would be "chocolate with milk" - and "advances of a sexual nature" towards GB captain Anne Keothavong.
Then, during the tie, he was heard to call both Keothavong and British player Johanna Konta "f****** bitches". The ITF said his "abusive and threatening comments" also stretched to match officials.
Nastase was thrown out of the tie and stripped of his accreditation but even then he threatened a journalist when leaving the venue in Constanta - an incident which the ITF has also taken into consideration.
An ITF internal adjudication panel has now delivered its verdict on the incidents, finding Nastase guilty of four charges.
It has banned him from being accredited at ITF-run events until the start of 2019. The ban will not, however, apply to Grand Slam, ATP or WTA tournaments which fall outside the ITF's jurisdiction.
The former world number one will also be unable to act in any official capacity in ITF team competitions, such as the Fed Cup, until 2021.
In addition, Nastase has been fined US$10,000. He has 21 days to appeal.
Nastase's evidence given to the ITF panel shows his comments regarding Williams' unborn child "were intended as a joke".
His mitigation also included saying that racism in Romania is not "as delicate an issue as it may be in other parts of the world". He said there was no previous evidence of him being racist and that friendships with former players Yannick Noah and the late Arthur Ashe showed he was not.
He also pointed out he had written letters of apologies to Williams, the British team and the journalist involved, Eleanor Crooks of the Press Association.
In the wake of the tie, Nastase issued a public apology but admitted "nothing can truly excuse my statements". He was not invited to the Royal Box at Wimbledon this year following his behaviour.
Romania defeated Great Britain in the tie to earn a place in next year's Fed Cup World Group II.
