The Belgium international is widely expected to leave the Sant'Elia during the January transfer window and has been reportedly attracting interest from traditional Serie A heavyweights Juventus, Inter and AC Milan.
It has been reported that Roma has also entered the race after a meeting between Cagliari president Massimo Cellino and Roma director of football Walter Sabatini, but Salerno insists that it was nothing more than a chance encounter.
"There is no agreement," the Rossoblu official told ASRomaRadio.it. "Cellino and Sabatini have spoken with one another in general terms and I can tell you that they met at the airport by accident. This story was born of that. But there is nothing concrete in relation to Nainggolan. We have not started any negotiations with Rome. I do not know to what extent the Giallorossi are interested in the player.
"We are not in a position to give an answer [to that question]. We have started several negotiations and within 10-15 days we will be able to give you a definitive answer. It can't even been said that we will give him away. For the moment, there is nothing concrete. I can assure you of that 100 percent."