The Bavarian giants fell to a shock 3-0 defeat to Red Bull Salzburg in a mid-season friendly on Saturday, just six days before their Bundesliga campaign is due to resume against Borussia Monchengladbach.
Guardiola admits that his side were outplayed by the Austrian league leaders, who scored three first-half goals, missed a penalty and had a shot cleared off the line.
"Our opponents were better than us. If we don't play well, plenty of teams are better than us. We learned some good lessons about ourselves," the official Bundesliga website quotes Guardiola as saying.
Bayern are currently seven points clear at the top of the table having dropped just four points all season.