The Manchester City forward will complete his move before the end of the transfer window and the Nerazzurri chief believes that the transfer is a “gamble” for the Rossoneri.
"He's a Milan gamble, we will see how it ends," Moratti told reporters.
"It could be a good move for them. I see it as a useful operation for Milan president Silvio Berlusconi for a thousand reasons. [He is] a good signing that we couldn't and didn't need to make because he's already played for us.
"I have to be honest, I'm a massive Inter fan, but I have no regrets."
Coach Andrea Stramaccioni looks set to unveil Ezequiel Schelotto and Zdravko Kuzmanovic at the club before the end of the transfer window and Moratti could not confirm if that would mark the end of the dealings.
He added: "We have squad needs. I don't know if our transfer market will come to an end with these signings."