City were crowned Premier League champions on Sunday, after United’s shock 1-0 defeat at home to West Brom.
Mourinho has spent more than £300million since he was appointed as United manager in 2016, but he is adamant that he won’t go overboard in terms of bringing in new players this summer.
“We are not going to spend more than we can. We are not going to do anything crazy,” Mourinho said, as reported by Sky Sports.
“We are just trying to improve a little bit more. That’s what we are going to try.
“Everybody will try to improve – like we did from last season. Last season we finished sixth and this season we are going to finish, hopefully, second.
“Next season, we are going to try to improve, but let’s see what happens. Maybe also City will invest massively and they don’t let the others close the gap to them, I don’t know.
“But it is not about us and them, it is about us and them and Liverpool and Arsenal and Chelsea and Spurs. It is not City and United. It is about the six.: