Mourinho did not name Chelsea but it was clear the United manager had his former club in mind as he launched another attack on the fixture list after he had already complained publicly this season about the scheduling of United's Premier League matches either side of Europa League ties.
“The busy period is for some clubs, not for everyone,” Mourinho said.
“If you analyse the fixtures there is no congestion for them. It looks like the fixtures are chosen to give rest for some and to create problems to others.
“But we are used to it because we are in the Europa League and the Europa League is a competition that creates more difficulties.”
Chelsea play three games in 10 days whereas Manchester United, Manchester City and Spurs play three matches in eight days and Liverpool have three fixtures in seven days.
Chelsea who are six points clear in the title race and have no European football to contend with this season have longer rest periods between matches and comparatively short distances to travel whereas Arsenal, whose manager Arsene Wenger has also denounced the schedule, play two games in three days at the start of the new year.
Meanwhile, Mourinho has said Morgan Schneiderlin has asked to leave Old Trafford and that he will not stand in the France midfielder's way if an acceptable offer is forthcoming.