Cassano was left out of Stramaccioni's squad for victory over Catania on the weekend.
"I wasn't there, so I can't tell you what happened," Moratti said.
"Cassano is a talent, as we know, and artists are a bit special. Basically we need to understand him.
"I see everyone is scandalised that it has been leaked, but what's worse is that it has gone on in the first place - not whether it has come out or not.
"There are 40 people in the dressing room so of course it can come out. It's a shame but obviously these things can happen. Ultimately these things mustn't happen though.
"Will he be fined? I'm not sure, I've left the decision on that one up to those who know what went on."