He said the four men had been working to bring security, democracy and prosperity to the Afghan people and to protect Canada's national security.
The Canadians were travelling in a military convoy on their way back from a patrol.
They were near the village of Gumbad in the Shah Wali Kot district, 75 kilometres north of Kandahar in southern Afghanistan, when their vehicle was destroyed in a roadside bomb.
A self-styled spokesman for the remnants of the Taliban regime, Yousuf Ahmadi, claimed responsibility for the attack.
Canada has 2,300 troops in Afghanistan.