Monday's sentence for Robert Schellenberg for smuggling 222 kg (489 lbs) of methamphetamines prompted Canadian Prime Minister Justin Trudeau to accuse China of "arbitrarily" applying the death penalty.
Trudeau has called several world leaders in recent days to share concerns about the case of Schellenberg and two Canadians that Beijing detained last month after a senior Chinese executive was arrested in Vancouver on a U.S. arrest warrant.
Speaking at a daily news briefing, Chinese Foreign Ministry spokeswoman Hua Chunying said Canada's "so-called allies could be counted on ten fingers" and did not represent the views of the wider international community.
"I can very clearly state that we are not worried in the slightest," Hua said of the mounting outcry, adding that a majority of Chinese supported severe punishment for drug crimes.
Schellenberg's sentence has further strained relations between China and Canada, already aggravated by the December arrest of Meng Wanzhou, chief financial officer of Huawei Technologies, on a U.S. extradition request.
Asked about Hua's remarks, Canadian Foreign Minister Chrystia Freeland noted that the 28-nation European Union had offered its backing to Ottawa.
"We're very pleased to have this support from the EU which ..., like Canada, believes in the rule of law," she told reporters ahead of a three-day meeting of Trudeau's cabinet in Sherbrooke, Quebec.
"Canada is clear about our principles and our position and we're also clear that it is a broad and deep relationship (with China)," she added.