The Colombia international is in the final months of a two-year loan spell with the Bundesliga champions and the likes of Juventus and Arsenal have been linked with a move for him in the summer.
Bayern have the option to make the deal permanent for around £37 million but appear unlikely to trigger the clause.
The 27-year-old has now suggested that his preferred option would be a return to the Merengues, who he joined from Monaco in July 2014 and made 111 appearances for ahead of his move to Bavaria.
"I have to think hard about what I'm doing [in terms of my future]," he told Cadena SER's 'El Larguero'.
"In Madrid, I have everything such as my house and people who love me.
"We will have to see what happens, but at the moment I have a contract with Bayern Munich.
"I just want to finish the season and we'll see what happens.
"I keep in touch with some Real Madrid players."
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