Cardiff have demanded an apology from FA Cup rivals Reading after City supporters were accused of racist and homophobic behaviour in Saturday's fourth-round tie at the Madejski Stadium.
An announcement was made over the public address system during the first half of the 1-1 draw for the "away fans" to desist with their chanting that was "not acceptable".
But Cardiff have said an initial investigation has shown there was no racist and homophobic behaviour from their supporters and are confident that the club's reputation will be fully restored.
"The announcement made at Reading this weekend was both damaging and hurtful and we would welcome a public apology from them to our supporters," Cardiff chief executive Ken Choo said in a club statement.
"I look forward to the conclusion of the police investigation, at which point I am confident that the reputation of our club and fans will be fully and unequivocally restored.
"Our football club prides itself on its respect of all people, irrespective of their background, beliefs or orientation.
"Cardiff is a diverse and welcoming, modern multicultural city and our supporters' actions reflect that at our games.
"We have a zero tolerance approach towards racist or homophobic behaviour and our supporters' conduct consistently reflects that."
Cardiff say they have a "clear picture of the facts" following conversations with Reading Football Club, Thames Valley Police and South Wales Police since the tie.
It is understood four Cardiff supporters were arrested and subsequently released prior to investigation for what could be considered as "unwarranted language".
Cardiff say this language could be heard taking place between fans of both clubs and was of an anti-Welsh/anti-English nature.
"We are extremely disappointed that Reading Football Club chose to label the behaviour as racist and homophobic (of which there has been no evidence)," said the Cardiff statement.
"We also question their protocol and procedure on the day and welcome a full investigation into its use for the benefit of both our clubs and indeed British football.
"Cardiff City is an inclusive club and embraces all cultures, ethnicities and people."
The PA news agency has contacted Reading Football Club for a comment on the matter.
The two sides meet again in Cardiff in the Sky Bet Championship on Friday and their fourth-round replay will be played at Cardiff City Stadium on Tuesday, February 4.
