Flying high at the top of the table, Guardiola has been criticised for failing to bring through City youngsters over his 18 months in charge.
But he insisted: "What we do compared to last season, we do it because I think it's the best way to win games. And, of course, to win games, you need great players.
"In the big clubs, there are great players and you have to buy them."
Asked if this season was an act of revenge for the criticism he copped from last term's trophyless campaign, Guardiola added: "I'm not here to convince the media. The media is convinced when I win. If I do not win, I will be criticized.
"When I retire, I can say: 'I went to England and we managed to play the way we wanted to play'."