Guardiola's side clinched the DFB-Pokal on Saturday, with a 2-0 win over rivals Borussia Dortmundin the final to add to their Bundesliga win.
Despite winning four trophies in his first season at the club, Guardiola's reign has been overshadowed by the semi-final elimination in the Champions League against Real Madrid.
However, the Spaniard revealed that there is still more work to be done ahead of next season.
"It's my fifth year as a trainer of a professional football team, my sixth year overall as a coach," Guardiola told reporters. "One year I was coaching the second team of Barcelona. After four years working with the first team of Barcelona, this has been the most important and challenging season of my trainer career.
"My German is not that good yet so I have to convince my players every time. After Bayern won the treble last season with Jupp Heynckes it was not easy for me.
"I have still not managed to make the team as I would like. There is still much work for me, but we can be proud of our four titles."
Guardiola signed a three-year deal when he joined Bayern Munich last summer.