Former Sunderland manager David Moyes behaved "entirely inappropriately" when he told BBC reporter Vicki Sparks that she might "get a slap", an independent panel ruled.
In a ruling released by the Football Assocation, a commission chaired by barrister Craig Moore accepted Moyes' comments were "attempted humour".
However, it said his actions were "wholly unacceptable".
He was fined £30,000 by the FA in June. The ruling has now been published.
Moyes' comments came following the Black Cats' home draw against Burnley in the Premier League in March.
The Scot was asked by Sparks if the presence of Sunderland's owner Ellis Short had put extra pressure on him.
Moyes responded to Sparks' question about Short's presence by saying "no", but after the interview added she "might get a slap even though you're a woman" and told her to be "careful" next time she visited.
Both Moyes and Sparks were laughing during the exchange and the former Everton and Manchester United manager later apologised to Sparks, who did not make a complaint.
Moyes, who resigned as Sunderland boss in May, subsequently expressed "deep regret" for his comment.
"That's certainly not the person I am," he said. "I've accepted the mistake. I spoke to the BBC reporter, who accepted my apology."
The commission's report
The report said: "It is no answer for Mr Moyes to say that his comments were intended as mere banter, or a joke, and were not to be taken seriously.
"We are satisfied from his oral evidence to us that he was at least irritated by what he considered to be a 'rude' question and that he wanted to convey the sense to Ms Sparks that, in asking it, she had crossed what he regarded as an acceptable boundary.
"When Ms Sparks asked him whether he felt under any additional pressure due to the presence of the club owner at the match, it was a reasonable question for a journalist to ask and one that he might have anticipated. It did not merit any censure.
"We find that the threat of physical violence was not one that a reasonable person viewing the video footage would seriously consider Mr Moyes would carry through with. Instead, the implication of his comments was that Ms Sparks had had her 'card marked'.
"We accept that Mr Moyes attempted humour, but it was still his intention to convey a point to Ms Sparks, which he succeeded in doing, and in an entirely inappropriate way.
"It is wholly unacceptable for a high profile Premier League manager whose statements/opinions are closely scrutinised, to threaten physical violence towards a journalist in the terms used by Mr Moyes, or at all."
The role of Greg Clarke
During the hearing, Moyes' lawyer Paul Gilroy QC, tried to have the case thrown out because of "fundamentally prejudicial" comments made by FA chairman Greg Clarke in the days after incident became public.
Gilroy said that when Clarke told reporters that "the disciplinary team will crack down on people who break the rules" and "will decide whether the rules have been broken and what an appropriate sanction should be" it meant Moyes would not be treated fairly.
But the panel said Moyes had a "fair hearing, free from any bias on the part of the commission".