The Red Devils are looking to sign a partner for Harry Maguire this summer.
Atalanta are expected to pay up to £21.5m (€25m) in their obligation to buy him permanently from Juve.
However, they would be willing to sell him on for around £34m (€40m).
"If you want to take up the challenge with them we need to strengthen our squad,' he said.
"We want to take the next step and it might be that we need a couple more to strengthen the squad."