While Chelsea have won 11 trophies in as many years under Roman Abramovich, City have only one League title and an FA Cup since 2008.
Mourinho told the London Evening Standard: "I think they have to do the same thing Chelsea did. Chelsea won three Leagues in six years, the Double, many FA Cups, Champions League semi-finals and finals.
"If they don't do that it's because football is football but they built a team for that with huge investment for three-four consecutive years, transfer window after window, improving their squad. They are in another dimension, but football is more than that and because of that no one knows what is going to happen."