Warnock had already accepted an FA misconduct charge in relation to his on-field behaviour following Leeds' Championship game at Millwall on 18 November.
However, he did not accept the standard £2,000 penalty for the offence and requested a paper hearing, which meant he was not required to attend.
The regulatory commission hearing decided that the fine should still be imposed, though.
Warnock was furious that referee Mark Halsey dismissed Luke Varney three minutes into the second half for an apparent elbow on former Whites loanee Adam Smith.