Motta, 29, has been linked with a move to free-spending Paris Saint-Germain, despite his agent claiming the Brazilian-born Italy international will see out his contract, which ends in 2013.
Moratti, however, is keen to retain the services of the player.
"Thiago Motta? He's one of our most important players," said the Italian supremo.
"This makes him non-transferable. We hope he won't leave."
Inter currently sit fifth in Serie A, six points behind league leaders Juventus.