Lazio president Claudio Lotito has made the claim this week.
"When I read the words of Lotito I almost fell over," Moratti said. "I rang my directors in the middle of the night and asked who this player was as I couldn't even remember his name.
"I don't know why Lotito is insisting with this story and I could get upset if he continues.
"Diakite may be a good player, but we have done nothing and we've not even thought about making a move for him."