The Premier League champions are said to be looking for a replacement for Paul Scholes and have been linked with the 26-year-old as well as Dutchman Wesley Sneijder.
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Heynckes said: “Bastian Schweinsteiger is held in high regard at this club.
"A year ago he was playing on the same level as players such as Xavi and Andres Iniesta.
"He is not for sale."
The 66-year-old also admitted his sadness at missing out on the signature of Chilean midfielder Arturo Vidal, who has left Bayer Leverkusen - Heynckes' former club - to join Juventus.
"I am absolutely disappointed because Arturo told me he wanted to join me at Bayern Munich," he said.
"I am, however, understanding of his situation and his desire to take on the challenge that is ahead of him at Juventus. They are a top club in Europe."
