"Messi is not for sale, not for sale," Laporta said. "He [Moratti] needs to forget about him. Did I tell Moratti? Yes. I won't even talk about such a move."
He also discussed Barca's deal for former Inter striker Zlatan Ibrahimovic.
"I understood that we could sign the Swede in the middle of July," Laporta revealed when asked about the swoop for Ibra.
"We had discussed it in June and we as a club had already analysed aspects of a deal which involved Eto'o and Ibrahimovic.
"But I realised that something could be about to happen when I spoke to Moratti one day in July."
Laporta was flying back to Spain after a transfer trip to Kiev, but took the opportunity to stop off in Milan.
"I called Moratti to say I would be in Italy and that I wanted to continue our Ibra chat. He invited me to his home to discuss the matter and it was while there that I knew that a deal would be done."
On the relationship between the two clubs, Laporta added: "There will be more deals for sure.
"If any proposed deals are of interest to either side then something will be done "