United have reportedly opened negotiations with the Bavarians for the Germany international, with reports on Tuesday claiming that the 24-year-old would have his current salary quadrupled to £260,000 per week should he join the Red Devils.
During a news conference in Munich today, Guardiola said: "[Karl-Heinz Rummenigge and Mathias Sammer] will do everything to keep Toni here. But it is up to Toni. He is a young person, it is his decision."
Kroos is contracted to the Allianz Arena club until summer 2015.