The FA reportedly used a lip reader to decipher what he said and his remarks were interpreted as offensive.
"Written reasons for the decision of the Independent Regulatory Commission will be published in due course".
Despite Mourinho being cleared this week, the FA could launch an appeal against the decision.
While there are grains of truth in Rooney's claims that the United squad has underperformed, and that this current shambles that the club finds itself in is more an indictment of the higher-ups, it is no secret that Mourinho has reverted to his third-season syndrome.
Budget giveaways will benefit rich families 14 times more than the poor
He stressed that a global agreement on digital tax was the best solution, but expressed concern at the slow progress of talks. This will make digital goods more expensive to consumers and may crimp on businesses' revenues.
West Indies opt to bat in 5th ODI
It was the West Indies' lowest total in a one-day worldwide against India , and their 10th lowest against any country. The in-form Sharma shared an unbroken partnership of 99 with skipper Virat Kohli , who struck 33 from 29 deliveries.
Oil rises 1 percent ahead of Iran sanctions
His comments come just one day after the country's foreign minister said USA sanctions will have "severe consequences". But, as a condition of waiver, Indian oil firms will reduce their imports to 14-15 million tonnes, the source said.
The victory over Newcastle was played amid a tense atmosphere with the club having denied a report earlier in the day that Mourinho was going to be sacked that weekend, regardless of the result.
Following the game, Mourinho raised his little finger towards a TV camera and appeared to say something in Portuguese.
In their original statement on October 16, the FA said: "It is alleged that his language at the end of the fixture, as captured by the broadcast footage, was abusive and/or insulting and/or improper".
They are now eighth on the log with 17 points from 10 games, and the former United star, who now plays for DC United believes the players have to do more.
Ianni celebrated wildly beside the field following Ross Barkley's injury-time equalizer for Chelsea in the 2-2 draw against United and, at one stage, goaded Mourinho and others on the United bench.