Berbatov, who has scored a record 48 goals for Bulgaria, has lost his starting spot at United even though the club took up an extra year's option on his contract in March. He joined United from Tottenham Hotspur in 2008 for 30.7 million pounds.
"I read the papers and I see they say 10 million pounds is my price. I go and talk with Sir Alex, and he says to me five million," the 31-year-old Berbatov wrote on his Facebook page.
"So who is telling the truth, what do you think? I love this club but I am not going to be useful to anyone if I am not playing. And I want to play.
"But for unknown reasons it's not going to happen, or my chances will be limited, so it's better for everyone if we say goodbye."
Berbatov scored 14 goals in his first season at United and found the target 12 times in his second season before finishing the following campaign as top goalscorer with 22.
However, last season he found himself behind Wayne Rooney, Danny Welbeck and Javier Hernandez in the pecking order for a starting place as Ferguson admitted earlier this year that he would not be able to guarantee the Bulgarian regular first-team action.
