A statement on the European governing body's official website read: "The Uefa control and disciplinary body today rejected the protests of Manchester United FC regarding the suspension of Darren Fletcher, and FC Barcelona regarding the suspension of Eric Abidal and the yellow card of Daniel Alves.
"The control and disciplinary body decided not to admit the protest submitted by Manchester United in relation to midfielder Darren Fletcher's red card in the UEFA Champions League semi-final second leg against Arsenal FC.
"Similarly the control and disciplinary body did not admit Barcelona's protest against the red card of Eric Abidal and the caution of fellow defender Daniel Alves in the semi-final second leg against Chelsea FC.
"All three players are therefore suspended for one Uefa club competition match and will serve their bans when Barcelona meet Manchester United in the Champions League final in Rome on 27th May."
Uefa has justified its decision not to overturn the suspensions because neither United or Barcelona met the official requirements of the appeal process.
Their rules state that appeals against red cards can only be considered in the case of mistaken identity.
"In reaching its decision, the control and disciplinary body concluded (i) that the protests had not been submitted within the required 24-hour deadline of a match for filing protests - as specified in the disciplinary regulations," the statement continued.
"And (ii) that even if they had been admitted they would have been rejected as unfounded as there were no grounds for contesting the referees' original decisions."
United and Barcelona both have three days within which they can appeal the ruling of Uefa's disciplinary body.