Mane was sent off after catching goalkeeper Ederson in the face during City's 5-0 win in the Premier League.
Senegal winger Mane was sent off after catching goalkeeper Ederson in the face during City's 5-0 win in the Premier League at the Etihad Stadium on Saturday.
"Sadio Mane's three-match suspension, which was effective immediately, remains in place after his claim of excessive punishment was rejected following an Independent regulatory commission hearing," said a statement issued by the FA.
"The Liverpool forward was dismissed for serious foul play during the game against Manchester City on Saturday."
The 25-year-old Mane will miss this weekend's Premier League match at home to Burnley as well as next week's League Cup/league double-header against Leicester City.
After the Manchester City match, Mane apologised to Ederson via Facebook, saying: "I hope and wish Ederson a quick recovery. I am so sorry he was hurt during our accidental collision on the pitch and am sorry for him that he could not complete the match because of it.
"I pray he heals fast and is back playing very soon!"
Ederson had raced out of his area to head clear a high bouncing ball when he was knocked to the ground.
He was carried off on a stretcher after receiving treatment on the field for around eight minutes.
A photograph of his injuries released after the match showed Ederson had had eight stitches inserted on the side of his face.
He returned to the City bench in the second half against Liverpool, and trained -- while wearing protective head gear -- on Tuesday ahead of Wednesday's Champions League match at Feyenoord.