The 31-year-old Italy international, who is currently representing his country at the FIFA World Cup, has been linked with a move back to Serie A rivals Samp.
Leonardi, however, stated on Saturday that the former Milan and Real Madrid frontman is committed to Parma.
He said: "Yesterday he (Cassano) sent me a text message that said: 'Forza Parma.' And we say 'Forza Cassano'."
Parma have sealed the outright signings of Jonathan Biabiany and Ishak Belfodil after the duo had previously been part-owned by the club.
An unpaid tax bill cost Parma a place in next season's UEFA Europa League, but Leonardi believes the club are in good shape and warned that any players who are not happy can move on.
He said: "Parma proved this is a solid club that wants to invest.
"It isn't a port of call. We only want motivated people who are happy to be here and play with pride. Anyone else can go."
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