Norwich manager Nigel Worthington said it was disrespectful of Sheffield United boss Neil Warnock to flick two fingers at him on Saturday.
Neil Warnock (left) was upset by Nigel Worthington
Warnock was unhappy after Worthington refused to shake his hand and told the Yorkshire Post: "I won't deny that I flipped my fingers in his direction.
"But only because I was so disgusted and frustrated at being humiliated by a fellow manager."
Worthington said: "There is a manager's code of conduct and that's not in it."
Norwich won Saturday's match 2-1 - further loosening United's grip on the second automatic promotion place in the Championship.
"I held out my hand for six or seven seconds but he kept on talking and turned his back," added Warnock.
"There was no mix-up, he even looked me in the eyes.
"I am sorry if it upset any fans. There was definitely no offence intended to anyone inside the ground apart from their staff."
Worthington did not see the incident until he watched it on TV afterwards.
He said: "I'm not bothered about it in any way, shape or form but I did find it a little bit disrespectful and unprofessional.
"What I can confirm is that I did shake hands with Neil Warnock after the game."
The incident has been reported to the FA.
Referee's chief Keith Hackett said: "With incidents such as this, if any of the four match officials has not seen it, then the match assessor can report it.
"Had it been seen during the course of a match the outcome would have been that the manager would have been sent to the stands."