The Portuguese coach is well-known for his mind games, and his latest comments could be seen as an attempt to protect his side should they struggle in the opening group stage game against the star additions at City.
"There are some things that money cannott buy - trophies and history," he told The Sun.
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"There is no team anywhere that can be compared with Real Madrid. None."
Mourinho contrasted the outlook of both clubs, suggesting that while City's owners will be desperate to announce themselves on the global stage with a Champions League crown, the pressure on him to deliver one at Madrid is tempered by the club's huge past trophy haul.
"This [City] is a team being created to lift the Champions League, that is their aim," he explained.
"A lot of top managers and clubs have never won a Champions League. So if I have won it twice and Real have won it a record nine times... well we should say 'thanks to God'.
"And if a third comes for me and a 10th title comes for Real Madrid this season - amazing.
“We will accept it all with a smile. But there is no pressure on us. There is no obsession to win it here.
"There are great clubs but the pressure and the expectation is the greatest here at Real Madrid. It is huge but it is an enjoyable pressure, not a suffocating one."
Mourinho did have praise for Mancini's team, however, describing them as "a powerful side", and singled out Carlos Tevez and Mario Balotelli as City's danger men for the tie.
"I don't like to speak about opponents individually but it's no problem to say that we respect Carlos Tevez a lot.
"I also know Mario Balotelli and the player he is because we were together at Inter for two years and so he certainly has nothing to prove to me."