The Swede signed with AC Milan last week.
“It is disappointing, because I think he'd have had more fun here," Mihajlovic told La Gazzetta dello Sport magazine Sportweek.
“It would've been good for him, for the city and the club, with the team playing to help set him up for goals. I have no complaints, because he had said that if he'd chosen Bologna, it would've been for me. I realise there are other factors at stake, including family commitments.
“Ibra did call me before making his decision, so he kept his word and remains a dear friend. It just means I'll have to beat him on the pitch now…"