Guardiola continues to be linked with a move away from the Allianz Arena after this season as his contract enters its final year, with Manchester City frequently rumoured to be considering his appointment despite having handed Manuel Pellegrini a new deal.
Pressure is also mounting on the former Barcelona boss to deliver the Champions League this term after two consecutive semi-final defeats, but Lahm says his commitment to the club's ambitions this coming season cannot be called into question.
"Those are all outside people," Lahm told reporters when asked about Guardiola's critics. "They should come here and see how meticulously he is working. The coach does a very good job. You just have to see him at bench during a game, and you know he does his job with heart and soul.
The former Germany captain believes Bayern's pre-season has set them up well for 2015-16 but has warned against any early complacency.
"We worked well and really hard, but you don't know where you are right after matchday one. You need a few weeks. All I can say is that we worked really well," said the 31-year-old.
Lahm also warned his team-mates that nobody should consider their spot in the starting XI safe given the intense competition for places.
"I'm working on a daily basis with him and you feel that he is 100 per cent with FC Bayern. His future doesn't have any effect on the team."
"It's not easy [on the bench] but I expect a professional approach. We are a team that wants to win everything - it is normal to have a certain competition within the squad.
"There will be disappointed players, but they have to continue working professionally - in training and on the pitch. You can be annoyed about the coach, but you have to give everything for the team."
Lahm also hinted at some continued tactical tweaks during the coming season, though he admits he would rather keep his midfield role than return to right-back.
"I will be playing both as a midfielder and right-back, it depends on the situation. It is great to have some variety and you can always learn something new. Nevertheless, it is no secret that I prefer to be a midfielder - nothing's changed there."
Finally, the 2014 World Cup winner reiterated his intention to see out his career in Munich rather than consider a move to Qatar or MLS.
"No, that's not for me. It's okay when other players do that, but I will end my career at FC Bayern, I won't leave the club," he added.
