Tevez is on a two-year loan deal that expires next summer and United are yet to sign him to a permanent deal.
The highly rated striker has been linked with a move away from the club in British press recently.
Maradona held talks with Tevez in Manchester last week.
Maradona told The Sun: “Tevez is worried about not being in United’s first-choice team.
“He’s got a challenge ahead of him to win a place among lots of extremely good players, including Wayne Rooney and Dimitar Berbatov.
“But I saw he was in good shape and told him the best way of showing his ability is to win the arm-wrestle against all the other players.
“Then he’ll give himself a chance with the Argentina team. I believe in his ability and I know he features in Sir Alex Ferguson’s plans.”