In front of over 94,000 fans, Barca lost to a Martin Petrov goal struck midway through the first-half.
Guardiola drew criticism for selecting a virtual reserve team for the game, but insisted afterwards: "I did not want to burden the senior players with minutes, taking into account the important commitments that will come.
"Despite the result, I'm happy with the way things turned out. It was good to give minutes to (Zlatan) Ibrahimovic. On Sunday, he will show what he can do. Gradually he will need to be connected to the team's game.
"We are fortunate to have a good base of young players. And through the market, we can see how highly valued they are around Europe."