United were held 0-0 by West Bromwich Albion at the weekend, leaving them five points adrift of fourth-placed Manchester City but with a game in hand. They host seventh-placed Everton on Tuesday and travel to bottom club Sunderland on Sunday.
United visit Belgian side Anderlecht in the first leg of their Europa League quarter-final on April 13 before hosting the return a week later.
A top four Premier League place is needed for access to the Champions League but United could grab a place in Europe's elite club competition next season by winning the Europa League.
"I just want to think that against Everton we are going to do what we tried to do (against West Brom), to try to play with our best team and try to win the match," Mourinho told British media.
"And after Everton we go to Sunderland with the same perspective...then the Europa League comes and I don't know.
"It's possible that you see me play in the Premier League with a team where I'm going to protect the players that I consider fundamental for the Europa League."
Manchester United have never won the Europa League or its predecessor, the Uefa Cup.