The 26-year-old has scored 12 goals in 23 appearances for the reigning Premier League champions this term but is believed to have grown frustrated over being largely used from the bench, recently confirming that he is keen to return to the Bundesliga one day.
"Edin is an important player for us," Mancini told Sky Italia. "At this time we have not spoken about the transfer market as there are still 10 games to go.
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"Dzeko, for me, is a great player. In Italy he could score more than 20 goals a season but he would cost €20 million (£17m), maybe more."
The Italian went on to play down the severity of his training-ground clash with Mario Balotelli prior to the controversial striker's January move to AC Milan.
"Those were lies reported by the tabloids and photographers who were here, because there was absolutely nothing," he insisted. "We were playing a training match, we were playing in opposing teams, he made a foul and I shoved him and sent him away.
"Mario has improved but I think he won't change at all; he will continue to make faults even when he is 30.
"But the important thing is that he understands that he can and should give more on the field, because the best is expected from a player like him every time."