Lewandowski, 33, has made it clear his intentions are to leave the Bundesliga champions this summer, expecting the club to sell him rather than lose him for free next year.
The Poland international has one-year remaining on his contract with the Bavarian giants and, having claimed he has no intentions to play for the club again, it has alerted several suitors, including Barcelona.
"My era at Bayern is over,' Lewandowski told reporters while on international duty with Poland.
"I don't see any possibility to continue playing for this club anymore.
"Bayern's a serious club and I believe they won't keep me, I don't want to play there anymore. A transfer is the best solution. I hope they don't stop me."
Lewandowski's remarks have not gone down well with clubs chiefs, in particular legendary goalkeeper Kahn, who has slammed the forward insisting he has shown a lack of respect.
"I can't tell you why Robert chose this path," Kahn told Sport1.
"Public statements like that don't get you anywhere.
"Robert became world footballer [of the year] here twice in a row - I think he should know what he has at Bayern."
"Appreciation is not a one-way street," Kahn added.
Barcelona have been heavily linked with the Bayern striker, while his international boss Czeslaw Michniewicz joked he'd like to see him sign for Liverpool, the club he supports.
It seems as though Barca have won the race for his signature, however, with a three-year deal agreed, according to The Sun.
Barcelona boss Xavi is keen admirer of the Polish star, but has previously claimed any deal would be difficult due to the club's ongoing financial struggles.
Since Bayern's sporting director Hasan Salihamidzic expressed an interest in signing Manchester City-bound Erling Haaland last summer, it is believed Lewandowski has become unsettled.
Should he leave Bayern, he will leave a legacy behind, having scored a staggering 344 goals in 372 matches during his time at the Allianz Arena.
He has won the Bundesliga title every season in his eight years with the club and also guided Bayern to the Champions League trophy in 2020.
Lewandowski scored 50 goals in 46 games for his current employers last season but it remains to be seen where the striker will be playing his club football next campaign.