The body also suspended 15 Godolphin horses from racing for a period of six months.
Zarooni, who has admitted the offenses, said, "I can only repeat that I have made a catastrophic mistake."
He said he was not aware that administration of steroids to horses solely for training was prohibited.
Sheik Mohammed bin Rasheed al Maktoum, ruler of Dubai and master of Godolphin, is "appalled and angered" by Zarooni's infraction, said racing manager Simon Crisford. He has ordered the trainer's yard locked down and a thorough investigation implemented to prevent further misdeeds.
Zarooni was hired by Godolphin three years ago to take part of the organization's training load from longtime conditioner Saeed bin Suroor.
Zarooni has had significant success in his short tenure with the Godolphin forces, including wins in the Dubai World Cup, the St Leger and the Irish Oaks.