Tuchel admits his squad is short with the season underway.
He said on Friday: "It is what it is. We will not panic, and we will not do things [for the sake of it]. We will not try to sign players that we are not 100% convinced. All signings so far are fantastic signings that help us.
"To be very honest, it is day-by-day business now to coach the team which is here and not lose your head as a coach about what could be.
"What sense does it make if I lose my head in the office and think about players that are not here? We are ambitious and work hard to strengthen our squad further, but we are calm, all the energy and ambition goes into the group that is here. We still have time. Maybe I can answer that question more precisely in September."
Tuchel also said: "I think we could use and strengthen our squad in depth and strength. But it's one thing that you wish for and another that is possible. It needs to be possible.
"We are looking for top quality, top personalities, good characters and competitors on the highest levels. You don't always get what you wish for, and that's why we are calm and ambitious at the same time. There are quite some days to go until the end of the transfer period. Everything is possible until the end."