Ciro Immobile was keen to stay at Torino but now has "other ambitions", according to the club's sporting director Gianluca Petrachi.
The Italian striker scored five goals in 14 games during a loan spell at Torino in the latter half of the 2015-16 season, and Petrachi had hoped to extend the 26-year-old's stay in Turin.
But Immobile, who has been a Borussia Dortmund player since joining the German club from Torino in 2014, is no longer settled at Stadio Olimpico Grande.
At new Torino manager Sinisa Mihaijlovic's first press conference since joining the club, Petrachi said: "Ciro Immobile wanted to stay a month and a half ago.
"Something has changed now, he's no longer convinced.
"He has other ambitions. We're not interested in investing in those who aren't convinced."