Josep Maria Orobitg claims Sir Alex Ferguson approached his client over a potential move to Old Trafford towards during the 2000/01 season.
Orobitg told The Sun: “The first club that went in hard for Guardiola was United. They really wanted him. Pep never wanted to talk about it.
“He kept his word, even when it involved Manchester United, a club that any player would have killed to negotiate with.
“United pressed me but I couldn't do anything. Pep hadn't yet explained to the Barcelona president he wasn't going to stay.
“United then gave us an ultimatum, they wanted a face-to-face meeting between Ferguson and Guardiola.
“They had to plan their team and couldn't wait any longer.
“Guardiola said no to the meeting and United abandoned their interest in Pep, and even got angry.
“After eight months of discussions with United, never with Pep, always me, and rejecting great financial terms, it all finished."