"Canada fully supports the United States' limited and focused action to degrade the Assad regime's ability to launch chemical weapons attacks against innocent civilians, including many children," he said in a statement.
"President Assad's use of chemical weapons and the crimes the Syrian regime has committed against its own people cannot be ignored," he added. "These gruesome attacks cannot be permitted to continue operating with impunity."
The prime minister called this week's chemical attack in the northwestern province of Idlib "a war crime" and "unacceptable."
US President Donald Trump launched the massive strike in retaliation for what he called a "barbaric" chemical attack he blamed on the government of Bashar al-Assad.
It was the first direct US action against Assad's government and Trump's biggest military decision since taking office.