United States Under-23 international Zelalem is out of contract at the end of the season and has been linked with a move to Dortmund.
The 19-year-old, who was born in Berlin, spent last season on loan at Scottish outfit Rangers.
Tuchel, however, has no plans to sign the teenage midfielder.
Asked about a deal for Zelalem, Tuchel told ESPN FC: "Right now? No. Not as far as I'm concerned.
"I don't think that we add somebody [in January].
"We had a lot of new players and it all takes time [to settle]. Even the German guys, who have a lot of experience, you have to admit that it took its time for them [to settle]. Every change in a club takes time.
"Right now, the group is growing together. We had to change a lot because we had too many injuries. We wish for more players to be healthy, more players on the pitch who can play week after week, they need those minutes.
"Right now, we don't want to add somebody."
Dortmund are sixth in the standings and return to action against Werder Bremen on January 21.