Mourinho and Co. have been forced to settle for Europa League football this season after previous boss Louis van Gaal was unable to deliver a top-four finish in the Premier League last term.
United are preparing for the last 32 in the Europa League - pitted against Saint-Etienne - and the manager is desperate to be back among Europe's elite, with the club currently sixth in the Premier League and five points adrift of fourth-placed Liverpool ahead of Wednesday's match against Hull City.
"Personally, I miss the Champions League," Mourinho, who has won the Champions League with Inter and Porto, told the press. "Every match I don't play in the Champions League means an incredible number of matches is not going up.
"I am the youngest one to be in the club of 100 [games in the competition]. Every time I don't play I am not happy.
"But obviously Manchester United is much more important than me. What matters is Manchester United and, as everyone knows, it's a club that belongs to the Champions League.
"We shall do everything possible to make sure we are in it next season.
"We have two chances to be there: one is by winning the Europa League, the other is by finishing in the top four. Both achievable, both difficult, but we are going to work hard for that."