The Premier League champion is a keen admirer of the Germany international and is hopeful of luring him away from his current club this summer, with initial talks over a possible deal having begun in Munich during the Champions League clash.
A recent report suggested that United has offered Kroos an annual salary of 16 million euros, but Struth has made it clear there has not been an official offer and has ruled out a summer exit.
"There has not been any official contract offer [from Manchester United]," Kroos' representative told Bild. "And there is absolutely no need to table an official bid either because Toni will stay with Bayern Munich at least until 2015."
The 24-year-old has a contract with Bayern until June 2015 and head coach Pep Guardiola stressed on Tuesday that the Bavarians are keen to hold on to the midfielder beyond the expiry date of his existing deal.
Nevertheless, contract renewal talks have so far been unfruitful and Kroos has refused to rule out leaving Bayern for a move abroad.