The former Barca and Bayern boss insists he only wants to work with players who are committed to Man City.
Pep Guardiola says Manchester City put in a lot of effort to keep Brahim Díaz at the club but the teenager was keen on securing a dream move Real Madrid.
The 19-year-old joined Los Blancos for a fee that could rise to £22m on Monday after entering the last six months of his City contract.
And, when Guardiola was asked about Diaz's departure, he said: "Like I said many times, I don't want people that don't want to stay here.
"We did with Brahim everything we have done with Phil (Foden) and with Jadon - important players and we did absolutely everything. The only one who decides to stay is Phil.
"We wish him all the best. Real Madrid is not a bad step, so hopefully he can take the minutes he wants and that he didn't want here for many reasons.
"He's a nice guy. Congratulations to the academy and the club for working so well, because important teams in Europe want our players."