Chelsea are understood to be resisting calls for an unreserved apology to Clattenburg who has not officiated since the allegation was made.
The Football Association yesterday announced it was taking no action and Ferguson, who spoke up for Clattenburg in the immediate aftermath of the allegation, has reiterated his belief that the official was not guilty of the charge.
"I did not believe it anyway," Ferguson said.
"The unfortunate thing for Mark is that he has had to carry that stain for the last few weeks.
"Everyone in the game is pleased for him now - apart from Chelsea.