Struggling Sunderland gave manager David Moyes their full backing on Tuesday but called his threat to slap a BBC woman reporter "wholly unacceptable".
The 53-year-old Scot apologised to Vicki Sparks even before the furore over their apparently light-hearted exchange a fortnight ago broke on Monday.
Thinking the camera and microphone were off following an interview after a 0-0 draw with Burnley, Moyes ticked Sparks off for asking an awkward question and said: "You still might get a slap even though you're a woman."
Both are then seen laughing.
However, Sunderland -- bottom of the Premier League -- issued a statement on Tuesday in which they took a dim view of Moyes's behaviour.
"The exchange between the manager and a BBC reporter was wholly unacceptable and such actions are not condoned or excused in any way," Sunderland said.
"David recognised this immediately, proactively bringing the matter to the attention of the CEO (Martin Bain) 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."