Premier League rules state that a 25-man squad must consist of no more than 17 foreign players, but Chelsea have one extra following the arrivals of Diego Costa, Didier Drogba, Cesc Fabregas and Filipe Luis.
Englishman Frank Lampard and Ashley Cole both left in the close-season, while Gary Cahill was the last high-profile home-grown player to join, but Mourinho is not interested in selling the much-maligned Torres.
"Three strikers is fundamental in the squad and we have three," he told Sky Sports News.
"'Nando [Torres] is one of them. We have a good squad. The perfect squad would be with this 18 players, not 17, but rules are rules and we are working hard, even here, to not have these kind of problems in the future.
"[We want] to have more English players in our squad which we are going to have in the future but in this moment we are still in the middle of this process.
"So at the moment we have to make a decision about one player not to be on that list."