The Spaniard presided over Bayern's first loss in 54 league matches as they were stunned by fellow Bavarians Augsburg at the SGL-Arena on Saturday.
Bayern's defeat changes little in Germany's top flight, they have already secured the earliest league title in the history of the Bundesliga by defending their crown with seven games to spare, breaking several records in the process.
Having walked their way to the title as they go about defending last season's treble, Bayern's previously unblemished record was spoilt by an Augsburg side picking up their first win in five outings.
Sascha Molders settled the encounter in the 31st minute, firing home after latching onto Daniel Baier's throughball as Bayern made several changes, with youngsters such as Mitchell Weiser and Pierre Hojbjerg handed rare starts.
Guardiola insisted the raft of changes were not the reason for the defeat, however, and urged his charges to quickly switch focus to Wednesday's UEFA Champions League second-leg tie with Manchester United at the Allianz Arena - poised at 1-1.
"There are no complaints," he told the club's official website. "We lost because the opponent was a bit better than us.
"We have already seen in the cup what a good team Augsburg is. We have fought and tried a lot. This is football, which is sport.
"You cannot always win. Sooner or later, a defeat would happen. We accept that and now need as soon as possible to prepare for the Manchester game.
"We did not lose because of the young players. Hojbjerg and Weiser were the best players on the pitch. They have trained a lot with us, they know our game and know what I want."
