Steve Bruce has been fined £2,500 following his critical comments about the dismissal of defender Michael Turner in Sunderland's defeat at Manchester City in December.
Bruce, who has also been asked to explain his comments after the game, during which he described referee Andre Marriner's decision to send off the defender for an aerial challenge with Gareth Barry as "obscene", "a joke" and "an outrage".
And the Football Association have punished the 49-year-old with the fine, while also warning him as to his future conduct.
An FA statement read: "At an Independent Regulatory Commission hearing, Sunderland manager Steve Bruce was fined for improper conduct.
"The commission took into consideration Bruce's admission of the charge and his previous exemplary record in relation to media comments."
Sunderland lost the match at Eastlands 4-3 and the club were quick to appeal against the Turner decision, which came in the closing stages.
However, the Black Cats' challenge to Turner's dismissal for catching the Manchester City midfielder Barry with his elbow was dismissed - and the defender had a fourth game added to his automatic three-match ban because the FA felt "the claim had no prospect of success".