The German international found himself in and out the Dortmund starting eleven last season, making 24 Bundesliga appearances in total and finding the net on four occasions.
His reported unsettled situation at Signal Iduna Park has prompted speculation over his future, with Eurosport claiming Arsenal and Southampton are keen while Sport Bild cite strong interest from West Ham United.
Dortmund boss Tuchel, however, has responded to the links by saying his midfielder is not for sale.
"With Ginter, I think everything is said," Tuchel told Sky Sports. "German clubs wanted to sign him and now English clubs want to sign him.”
"I don't know if everything is true or it is just rumours but we made our point clear - Matthias is our player and stays our player."
Ginter is predominently a talented defensive midfielder though he is also capable of playing in defence, either in the middle or at right-back.
Arsenal have plenty of defensive-minded players following the arrival of Grant Xhaka, though Southampton could be in the hunt for a new holding midfielder after Victor Wanyama joined Tottenham Hotspur.
West Ham, on the other hand, have made signing a new striker their summer priority but their attempts to sign AC Milan’s Carlos Bacca has so far proven rather futile.