The i says Amorim has been informed by United's top brass that he will have only £20m to buy players this summer.
United's issues with the Proft & Sustainability rules is said to be behind the modest transfer budget.
Any extra money will have to be raised from player sales, which could include highly-rated youngsters Kobbie Mainoo and Alejandro Garnacho.
Amorim stated on Friday: "We know with the moment of the club, I have to understand all of these problems but that problem of our club is not new.
"You knew the rules of fair play, we have a problem there at the moment but that cannot influence the way I coach the team and prepare for the next game. So my focus is on that and not the other things.
"Here its simple: to do something we need to sell players."