Pellegrini insisted that Chelsea were the biggest spenders in the January transfer window having bought Nemanja Matic, Mohamed Salah and Kurt Zouma, while also paying the biggest amount since owner Roman Abramovich bought the club.
But Mourinho said: “Everyone knows what Manchester City is. Pellegrini was doing some comments about the money we spent.
“I think he’s a fantastic coach and I respect that a lot. On top of that outside his football career, he’s an engineer and I don’t think an engineer needs a calculator.
“It is easy to understand that this is to work with the Financial Fair Play, what I call fair Financial Fair Play. There are no arguments against that.
“This is what we’re doing, others will do the same. We are building the team for the next decade if possible and they have a team to win now.
“They don’t have a team for 10 years, for now. Experience, potential, power, not worried about Financial Fair Play because in the summer they just spend. We don’t need a calculator for this, it’s easy - plus 23.”