Chelsea regret the impact that the claims of inappropriate comments have had on Mark Clattenburg, but did not apologize for filing the complaint.
Chelsea FC have issued a statement regarding the events involving Mark Clattenburg and his alleged comments during the tie against Manchester United. The full release can be found here, the meat of the statement is as follows:
The club regrets not having given more consideration before issuing a statement on the evening of Sunday 28th October. The club also regrets the subsequent impact the intense media scrutiny had on Mark Clattenburg and his family. The referees accept that, given Chelsea FC had received a good faith claim from one of their employees, the club had an obligation under FA rules to report the allegation.
I'm sure some in the media will get on the club for the lack of an apology, but frankly, anyone writing that ought to be run out of their job. If Chelsea had a complaint from any member of their club about potential racism, they were absolutely obligated to report it to the FA. Anybody who feels Chelsea were in the wrong for filing the report should simply google the words "Joe Paterno."
What's also worth remembering here is that this should not reflect negatively on either of the Chelsea players involved. There was not enough evidence to charge Clattenburg with any sort of offense in this case, but that should not lead any reasonable human being to conclude that the Chelsea players simply made up the incident for some sort of vengeful reason. We don't, and likely never will know what was really said or thought to prompt these charges.
Hopefully this puts this whole incident to bed, and I'd really hope that Chelsea fans don't abuse Clattenburg when he returns to Stamford Bridge. He's generally a decent referee, and there should be no reason for any fan to bring up this incident if he's assigned to a Chelsea game again.