Guardiola spent four years as manager of Barca up until the summer of 2012 and managed to win every competition that his side competed in.
"[Barcelona] are the best in the world. And that was prompted by Pep, that is clear. He did an excellent job," Klopp told El Pais.
"But he will not always have players like that at every club and he knows it. Now he has to teach us how to do it when the players are somewhat less good."
Guardiola will take charge of Bayern at the end of the current campaign.