'We believe it is inhumane and inappropriate, and wherever the death penalty is considered with regard to a Canadian we speak out against it, ' she said.
The death sentence has deepened tensions between China and Canada, with the two countries at odds for the past two months.
The founder of Chinese tech giant Huawei is thanking Canada's justice system for the kind treatment of his daughter, the company's chief financial officer arrested last month in Vancouver on a US warrant.
Beijing pays little attention to foreign countries' criticism of a Chinese court's decision to issue the death penalty for Canadian national Robert Lloyd Schellenberg, Chinese Foreign Ministry spokeswoman Hua Chunying said on Wednesday at a press briefing.
The Canadian was accused of smuggling more than 200kg of methamphetamine into China.
Only hours after Canada cautioned its citizens about traveling to China due to "arbitrary enforcement of local laws", China struck back on Tuesday with an advisory of its own, warning Chinese citizens to exercise caution when traveling to Canada.
"I can't tell you the relationship between Mr. Schellenberg's last appeal procedure and sensitive events which happened in Canada, " Zhang said, but he described the timing of Schellenberg's appeal and retrial as "very significant".
Schellenberg had appealed against an original 15-year prison sentence issued in November, but the court in Liaoning province sided with prosecutors at the retrial that the punishment was too light.
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Speaking at a daily news briefing in Beijing, Chinese Foreign Ministry spokesperson Hua Chunying said Canada's "so-called allies could be counted on 10 fingers" and Canada's views did not represent those of the wider global community.
It urged Chinese citizens to consider their personal circumstances and "fully assess the risks of going to Canada for tourism".
"We have very clearly outlined the case's facts and its seriousness", she added.
State media has played up coverage of his case following the deterioration in relations with Canada.
Schellenberg plans to appeal, his lawyer Zhang Dongshuo told AFP.
Rights groups condemned the Schellenberg sentence while Guy St-Jacques, who was Canada's ambassador in Beijing when Kovrig worked there, expressed concern at how quickly the courts had acted.
Zhang said there was insufficient evidence to prove Schellenberg was part of a drug syndicate, or that he was involved in the smuggling of methamphetamines.
A senior Canadian government official said Chinese officials have been questioning Kovrig about his diplomatic work in China, which is a major reason why Trudeau is asserting diplomatic immunity.
She rhymed off a list of countries - Germany, France, the Netherlands, the European Union, the United States, Britain, Australia, Estonia, Lithuania and Latvia - for "publicly coming out and speaking against these arbitrary detentions".