Maple Leaf Foods chief executive Michael McCain said his colleague’s wife and son were among the 57 Canadians who died.
Without explicitly naming Mr Trump, he suggested “a narcissist in Washington” ultimately caused the air tragedy.
Canadian PM Justin Trudeau has vowed to “pursue justice” with Iran.
In a thread on the company Twitter account, Mr McCain said: “US government leaders unconstrained by checks/balances, concocted an ill-conceived plan to divert focus from political woes.”
Mr McCain, whose company employs more than 11,000 people, said the death of his colleague’s family members was “the collateral damage of this irresponsible, dangerous, ill-conceived behaviour”.
He also criticised US efforts to dismantle the 2015 nuclear deal between world powers and Iran.
On Saturday, Iran said it “unintentionally” shot down the Ukrainian plane.
The apparent blunder came hours after Iran launched missile strikes on two airbases housing US forces in Iraq in retaliation for a US drone strike that killed Iranian Gen Qasem Soleimani.