Federico Pastorello held talks with Inter Milan in Italy on Tuesday over a potential deal for the Belgium international striker.
After the meeting in Milan, Pastorello told reporters: "Lukaku is a dream, a difficult one to make happen as such, but I believe nothing is impossible.
He was then asked if Inter are actively trying to sign him, adding: "Yes, he's [Lukaku] publicly expressed his plans and desires. We'll see what happens."
United are adamant they will receive at least £80m for the 26-year-old.
However, with transfer funds reportedly light, the Red Devils could be tempted to part with less.