Champions League hopefuls City and United will clash in the Manchester derby at the Etihad Stadium on Thursday in another installment of Pep Guardiola versus Mourinho.
And Mourinho heaped pressure on rival Guardiola – who went to Old Trafford and won the reverse game in September – amid United's congested fixture list.
"They play now one game a week until the end of the season while we have the [Europa League] semi-finals which are very important for us," Mourinho said.
"Obviously to play one match per week brings teams and players to other levels, so it's more difficult for us but we are going to try."
Mourinho continued: "It doesn't matter what happens in terms of titles we win or don't win.
"I always feel that the season is very important for me, the players and the club.
"I would say this can be the first season of the next five or six or seven. It can be the first season of better years.
"And the reality is even in the first season of better years we won already [the Community Shield and EFL Cup], and if we manage to win the Europa League and in August to play the European Super Cup against the Champions League winner, it will be magnificent."