The 20-year-old Albania international is currently on loan at the Saint Mary’s stadium from Chelsea and has impressed so far this season.
Broja has made 20 appearances under Ralph Hasenhuttl in all competitions and scored seven goals.
Southampton are keen on making Broja’s move permanent but Tuchel gave little away when asked about his long-term future ahead of Chelsea’s trip to Brighton and Hove Albion on Tuesday.
"He is our player, he is doing good, but at the same time it is only halfway through the season so he needs to continue to improve and make his statement at Southampton,” Tuchel said.
"They are our players for a reason, they have quality and a mentality.
"Armando is getting better and better. He is a unique player with unique strengths: strong and robust and a goalscorer.
"Now is not is not the time to talk about summer. He has to stay calm and keep on improving."
Broja has been at Chelsea since the age of nine and has come through the youth ranks to reach this far.
He made his senior debut for Chelsea in a 4-0 Premier League win over Everton in the 2019/2020 season but that remains his only competitive appearance for the Blues.
Broja signed a new five-year contract at Chelsea last summer before moving to Southampton.
