United have reportedly been tracking goalkeepers from around Europe as they expect Edwin van der Sar will retire at the end of the season.
Holzhauser told BILD when asked about interest from United in Adler: “That’s true. He has even been scouted.”
But Holzhauser remains confident that Adler could sign a new contract with the club.
“We know there are people on their way, but we are relaxed,” he said.
“We have been talking to Rene about a new deal. We want to sign a new contract with him in the next few months.”
United have also been linked with a shock move for Liverpool goalkeeper Jose Reina in recent weeks.