The European champions have been heavily linked with the Belgium international, who was on Chelsea's books from 2011 to 2014.
Inter reportedly rejected Chelsea's second offer worth £85m (€100m) along with Marcos Alonso for Lukaku, with the Blues set to table another bid believed to be worth £102m (€120m).
Tuchel would not be drawn on the situation following Chelsea's 2-2 friendly draw with Tottenham.
“I will not talk about players who don't play in my squad," Tuchel told reporters. "He's a fantastic player but he's an Inter player and I will not talk about him in this situation."
Chelsea are yet to make any major signings this off-season but have also been linked with a big-money move for Erling Haaland.
Tuchel added: “You can imagine a lot of players want to come and join but we will not talk about that.
“The board isn't offering players, that's not how it works. We talk to the board about players, have our own opinions, and in the end we target players who in our opinion could make our squad strong, which is quite a challenge.
“There are some players of which we think they can be a good target and improvement in our squad. I will not comment on names as I don't like it when other coaches speak about my players. So hopefully you understand that.”
Lukaku scored 24 goals from 36 games in Serie A as Inter won the Scudetto in 2020-21.