Speaking after a meeting with Inter chiefs in Milan on Wednesday night, Pastorello admitted the two clubs are in talks over the potential transfer of the 26-year-old Belgium international.
Sky in Italy are reporting the Serie A club have identified Lukaku as their main target for the summer transfer window and are keen to bid for a one-year loan deal with an obligation to buy for a total of £62.8m next year.
"It was just a chat," Pastorello told Sky in Italy. "I spoke with the director [Giuseppe Marotta] to understand the club's intentions with the player. They will take the decisions, we can't put a time frame on it.
"What is clear is that if Inter want the player, they will need to get a move on.
"Inter are seriously trying to sign him, they are all out for him. Goals are not always there to be reached, but it's a declared target. At the moment, it remains a complicated dream."