Leicester chairman Vichai Srivaddhanaprabha has described the decision to reject Jamie Vardy's appeal against his red card as "unfair".
Vardy was sent off at Stoke on Saturday for a two-footed challenge on Mame Biram Diouf, with referee Craig Pawson deeming the foul reckless enough to warrant a straight red.
The champions contested the call, but a Football Association disciplinary panel upheld the decision and Vardy will now serve a three-match suspension.
Srivaddhanaprabha said via his Instagram account: "I am so sorry for the unfair judgement of referee to Vardy and more sorry that our appeal was rejected. This kind of judgement distort the charming of English Premier.
"I spend a lot of time and effort to make my beloved LCFC a success, but this incident made me feel dispirit from football.
"Anyway, we move on now and it's time that we need to be unity together and cheer up (louder than before) to our team no matter what happen, we are fearless and never quit!"
The FA's verdict will come as a blow to Leicester boss Claudio Ranieri and his side as they struggle to live up to the expectations as defending Premier League champions.
The Foxes have won only four of their opening 17 league games of the campaign and are just three points above the relegation zone. Now they face the prospect of entering their festive fixtures without Vardy, whose own form has reflected Leicester's change in fortune.
The former non-league striker broke the Premier League record by scoring in 11 consecutive matches last term, but went 16 games without a goal before ending his barren run with a hat-trick in the recent victory over Manchester City.
However, he will miss the Boxing Day clash against Everton, the New Year's Eve meeting with West Ham and the trip to Middlesbrough on January 2.
Vardy will be available again for the FA Cup third-round tie against the Toffees at Goodison Park on January 7.