The 22-year-old joined Bundesliga side Cologne on a six-month loan deal on Tuesday.
Tosic said: “I believe I haven’t had my final say at Manchester United and that my performances with Cologne will be my ticket back to Old Trafford.”
Tosic’s agent, Zoran Pavlovic, said: “There were some offers to buy out Tosic’s contract, but Manchester United were unwilling to go for that option.
“Sir Alex Ferguson is obviously counting on him in the future, but for now, Tosic has been sent out on loan.”