The Netherlands international is believed to be a transfer target for the Bundesliga champions, with the club allegedly looking to sign him over the next week or so.
However, Hainer has claimed that Bayern already have a "very, very strong team" and are therefore unlikely to make any new acquisitions before the winter transfer window closes for business.
"We have a very, very strong team - and I don't see any reason why we should still do something in winter," Hainer told Sky Deutschland.
De Jong, who has also been linked with a move to the Premier League, has scored once and registered two assists in 25 appearances in all competitions.
The 24-year-old has scored 10 times and registered 14 assists in 118 appearances for Barcelona since making the move from Ajax in June 2019. body check tags ::