The News of the World says he has not appeared in the League this term and United boss Sir Alex Ferguson is considering a loan request from Zaragoza.
Macheda, 18, is likely to make the move to Spain until the end of the season.
Newcastle are also interested in taking Macheda on loan but it is thought Ferguson will see La Liga as a better learning environment than the Championship for the young striker.
Zaragoza's sporting director Pedro Herrera said: "With our money problems it is necessary to search for loan deals and these have worked well in other years. Macheda is on our agenda, that is certain."