TORONTO — Canada tried to turn up pressure on China on Saturday over the detention of two Canadians caught up in a struggle between global superpowers, with its foreign minister calling their imprisonment “arbitrary” and “a precedent that is worrying not only for Canada but for the world.”

China seized the two Canadians, the former diplomat Michael Kovrig and the entrepreneur and writer Michael Spavor, shortly after Canada detained a Chinese telecommunications executive at the behest of the United States. The detentions of Mr. Kovrig and Mr. Spavor have rattled Canadians, many of whom do business and have family in China, and the government stressed that it was working feverishly for their release.

“We also believe this is not only a Canadian issue,” Foreign Minister Chrystia Freeland said in a conference call on Saturday. “It is an issue that concerns our allies.”

Canada is in a tricky spot, boxed in between its two largest trading partners and worried about having to choose sides. After feeling burned by negotiations to replace the North American Free Trade Agreement, the country is trying to strengthen trade relations with China to lessen dependence on economic ties to the United States.