The Belgian forward is desperate to go back to Inter following a poor season at Chelsea but the club's CEO Beppe Marotta feels that lots must still be done if the transfer is to be completed.
Marotta said: "It's a feasible path, but there are some difficulties and we need to evaluate whether there's a chance to make it. We won't announce Lukaku's return today."
Paulo Dybala is another target for the Serie A club but Marotta warned that the club must think about finance before bringing players in.
He said: "Lukaku and Dybala are our targets, but we need to consider financial issues.
"We are in talks with these two players and we'll be happy if we sign them. If not, we'll consider different targets. The single player is not important, what matters is the group and this is already a solid team."
Marotta did confirm that goalkeeper Andre Onana and playmaker Henrikh Mkhitaryan are close to joining and promised fans that they will see a competitive team in action next season.
Asked about other transfer plans, he said: "We will have new signings, but I don’t know who they will be. Mkhitaryan will be official in the next few days, the same goes for Onana.
"We are evaluating a bit of everything, also players from the Primavera team who became Italy champions. We know that we must wait for young players and build a strong team. We’ll try to offer [manager Simone] Inzaghi a strong team from the start of the season."