Lahm said that he has been impressed with Guardiola's first training sessions with Bayern and that the players understand what he is trying to do.
"Every trainer and their backroom staff do things differently," Lahm told Bundesliga.com.
"There's always something new when a new coach comes in. Team talks, training - it's all new. [My] first impressions are really positive.
"He communicates really well in German and fills in the gaps in English. We're looking ahead with great optimism."
Previous Bayern coach Jupp Heynckes completed the treble in his final season before Guardiola took over.