Guardiola signed a new deal with Barca last week.
"We are having a very good run in La Liga and we don't top the table only because of [Pep] Guardiola's Barcelona," Mourinho said.
"Pep is a very prestigious coach. The time one has coached isn't important; it's what you achieve that counts. Guardiola has done enough to be regarded as one of the best coaches in the world."