The German finished last season on a high after scoring the winner in the Champions League final against Manchester City.
But Havertz has failed to take that momentum into the current campaign, and Tuchel has told him he must work hard to regain his place in the side.
Asked about Havertz not currently playing at his best level, Tuchel said: "That's a fact.
"He does everything to reach his level again and we will do everything to help him.
"He is an important player for our squad and it will be like this at the moment.
"He had many games to start with, he started strong in the season. He was very strong in pre-season. The story has not changed.
"But he lacks, as simple as that, the statistics of decisive things, of goals and assists and he needs to fight his way back into the team.
"And he gets minutes and this can happen anytime.
"We trust in him and we believe in him and the rest has to come from him and he's willing to do so.
"He's in good shape and a good mental state. He knows what he's fighting for and that's the situation right now."
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!