The Blues lost 1-0 to Pep Guardiola’s men in Saturday’s Premier League fixture at the Etihad Stadium.
Kevin De Bruyne’s second-half effort was enough to seal victory for the champions, who are now 13 points clear of Chelsea at the top.
Unlike his De Bruyne, Lukaku was unable to have any effect on the game and Tuchel acknowledged that he had been left unhappy with his efforts.
“We had eight or nine offensive transitions, but zero touches in the box.
“That was a big problem today, the performance of our front players. A lack of position, timing and composure. We lost too many balls too easily.
“Romelu Lukaku sometimes needs to [deliver] the service. He is included in this, he had many ball losses in very promising circumstances. He had a huge chance.
“Of course we want to serve him, but he is part of the team, and the performance up front, we can do much better,” Tuchel stated in his post-match comments.