The inquiry concluded that the 31 officers who had their hair cut last week should be fined £200 and the two who organised it will be investigated for misconduct.
"It is deeply disappointing and frustrating that my officers have fallen short of the expectation to uphold Covid-19 regulations," Det Chief Supt Marcus Barnett said.
"Although officers donated money to charity as part of the haircut, this does not excuse them from what was a very poor decision."
Despite lockdowns being brought in across the UK, there has been concern that many people are not abiding by the rules, meaning the virus keeps spreading.