Donald Trump's ambassador to the UK has been accused by a government watchdog of making "inappropriate or insensitive comments on topics such as religion, sex, or colour."
A 43-page report by the US state department's Office of the Inspector General, also suggested Woody Johnson's management style had a "negative effect" on some staff, and recommended a "more thorough review".
However, leadership at the state department disagreed and said a review was not warranted.
Phil Reeker, acting assistant secretary of state for Europe, told the watchdog Mr Johnson was "well aware of his responsibility to set the right tone for his mission and we believe his actions demonstrate that."
Mr Johnson had watched a video on workplace harassment, as had senior staff at the embassy in London, the state department said.
In a letter to the watchdog Mr Johnson said: "If I have unintentionally offended anyone in the execution of my duties, I deeply regret that, but I do not accept that I have treated employees with disrespect or discriminated in any way. I believe that team cohesion in our mission is better than ever."
He added that there was an "absence of any official complaints against me" and that the wide-ranging watchdog report had been "generally positive" about his tenure.
The report did not give any detail of alleged incidents involving Mr Johnson, a billionaire NFL owner and friend of Mr Trump.
But last month CNN reported that Mr Johnson had pushed back on hosting an International Women’s Day event, asking why he had to do "a feminist event".
CNN also reported that, ahead of a Black History Month event in 2018, Mr Johnson allegedly asked if the audience would be “a whole bunch of black people".
Mr Johnson denied the claims.
The watchdog report contained no mention of another allegation that Mr Johnson had tried to persuade the British government to have the British Open played at Mr Trump's Turnberry golf course in Scotland.
That allegation was denied by Mr Trump, Mr Johnson, and the British government.
According to the watchdog report "some staff were impacted by the Ambassador's demanding, hard driving work style and it had a negative effect on morale in some embassy sections."
He was said to have seen push back from diplomatic staff as "resistance" and to have "implied that he might have them replaced".
The situation improved when a new deputy chief of mission arrived in January 2019, the report said.
Following the state department's decision not to pursue a "more thorough review" the watchdog said the situation was "unresolved".