It is the first time the Dutch government has given details of the raid, which targeted an alleged IS bomb factory in Hawija, north of Baghdad.
Large, unexpected secondary explosions meant the death toll was higher than anticipated, a ministry statement said.
Dutch sorties in Iraq ended last year.
The IS facility hit in Hawija on the night of 2 June 2015 was believed to be producing vehicle-borne improvised explosive devices (IEDs) used to attack coalition forces, the statement said.
