Milan signed striker Ibrahimovic on loan from Barcelona and acquired Brazilian forward Robinho from Manchester City on the final day of the transfer window.
Mourinho has been paying close attention to Milan's transfer dealings as his Real Madrid side will face the Rossoneri in Champions League Group G, where Auxerre and Ajax also lie in wait.
"With Ibrahimovic and Robinho, this is another Milan," Mourinho told Gazzetta dello Sport. "Robinho and Ibrahimovic are among the best in the world. Certainly Milan is much stronger than it was a year ago.
"The Rossoneri are among the teams that can win the Champions League."
Mourinho, who departed Inter in the summer after guiding the Nerazzurri to a Coppa Italia, Serie A and Champions League treble, has no regrets over his decision to leave Italy.
"I don't think any Italian coach misses me just as I don't miss them," he said. "I do speak to [Inter Milan president Massimo] Moratti every week. We are friends. He is part of my history just as I'm part of his.
"I hope with all my heart that Inter wins the Scudetto, the Coppa Italia and the FIFA Club World Cup, but not the Champions League. But I am a professional and when I end a chapter, I end it without regrets."