Sunderland have given their support to boss David Moyes but say his comments that a BBC reporter might "get a slap" were "wholly inappropriate".
Moyes has apologised for what he said to Vicki Sparks after an interview following a draw with Burnley in March.
The Scot has also revealed that the club knew about the incident soon after it occurred.
"Such actions are not condoned or excused in any way," said Sunderland in a statement.
"The exchange between the manager and a BBC reporter was wholly unacceptable.
"David recognised this immediately, proactively bringing the matter to the attention of the CEO and apologising to the reporter.
"The club also spoke with both a senior figure at the BBC and the reporter personally, expressing its profound regret over what had occurred.
"The matter was treated with the utmost seriousness from the outset and the swift and decisive action taken by the club and the manager at the time ensured that it was resolved to the satisfaction of the reporter and the BBC, which was the priority.
"With both the BBC and the reporter agreeing that appropriate action had been taken at the time, the club continues to fully support David in his role as manager of Sunderland AFC."
In the interview in question, Moyes was asked by Sparks if the presence of owner Ellis Short had put extra pressure on him.
He said "no" but, after the interview, added Sparks "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 the reporter, who did not make a complaint.
The Football Association has written to Moyes to ask for his observations on the incident.
His comments have been criticised by shadow sports minister Dr Rosena Allin-Khan and Women in Football.
Domestic violence charity Women's Aid has also been critical and urged the FA to act.
Chief executive Polly Neate said: "We cannot be complacent about remarks like these from influential men.
"We urge the FA to act swiftly and take this opportunity to send out a clear and strong message to the footballing community that there is no place for sexism and misogyny in modern football."
Speaking in a news conference on Monday, Moyes said: "I deeply regret the comments I made.
"That's certainly not the person I am. I've accepted the mistake. I spoke to the BBC reporter, who accepted my apology."
The BBC confirmed that Moyes and Sparks had spoken about the exchange and the issue had been resolved.
A spokesman said: "Mr Moyes has apologised to our reporter and she has accepted his apology."
Sunderland are bottom of the Premier League on 20 points, eight points from safety, going into a game at Leicester City.