Martinez has been tipped to swap Serie A's Inter for LaLiga champions Barca, who are determined to sign a long-term replacement for veteran forward Luis Suarez.
Despite Barca's reported interest amid the coronavirus pandemic, Inter sporting director Piero Ausilio insisted Martinez will not be sold for anything less than his €111million buyout clause.
Asked about Argentina international Martinez, Moratti told Sportmediaset: "You can't hold someone who has the idea of being somewhere else.
"That would put him in a position to remain involuntarily or, in any case with a different impulse, in the same place."
While Martinez's future has dominated headlines, Brescia sensation Sandro Tonali has emerged as a target for Antonio Conte's Inter.
The 20-year-old midfielder – likened to Italian great Andrea Pirlo – has also been linked to the likes of Juventus, Barca and Manchester United.
"Right now here maybe we have to see how [Christian] Eriksen is doing, but otherwise he is a great midfielder," Moratti said. "Then you will need someone on the wings, certainly."