Boateng is currently facing a battle to be fit for this summer's World Cup after sustaining an adductor injury against Real Madrid on Wednesday night.
However, reports have suggested that United are considering a move for the Germany international, and Boateng has acknowledged that he is unsure over where to continue his career.
The 29-year-old told Socrates Magazine: "I've experienced everything at Bayern, and I am slowly coming to a point where I must answer myself certain questions.
"What are the goals I have not reached yet? Do I, time and time again, want to prove myself at the same club with the same pre-conditions? Those are not necessarily classic questions regarding the career, but vital questions and, in the end, questions that drive people."
Boateng is closing in on seven years spent at Bayern, with six Bundesliga titles, three DFB-Pokal trophies and the Champions League being won during that time.