"We expect Iran... to bring the guilty to the courts," the Ukrainian leader wrote on Facebook, calling also for the "payment of compensation" and the return of remains.
Tehran admitted Saturday that it accidentally downed the Ukraine International Airlines (UIA) plane, killing all 176 people on board on Wednesday, shortly after launching missiles at bases hosting US forces in Iraq.
"We hope the inquiry will be pursued without deliberate delay and without obstruction," Zelensky added
He urged "total access" to the full inquiry for 45 Ukrainian experts, and in a tweet also sought an "official apology".
Iranian President Hassan Rouhani said earlier Saturday that Tehran "deeply regrets this disastrous mistake".