At 9:46 a.m. ET (1346 GMT), the Toronto Stock Exchange's S&P/TSX Composite index was down 24.27 points, or 0.15 percent, at 16,384.89.

Eight of the index's 11 major sectors were lower, with financial down 0.3 percent.

Top drags among financials were shares of Toronto-Dominion Bank, which dipped 0.4 percent, and a 1.2 percent drop in shares of Fairfax Financial after quarterly results.

China announced retaliatory tariffs on $60 billion worth of U.S. goods ranging from liquefied natural gas to some aircraft and warned of further measures, signaling that it won't back down in a protracted trade war with Washington.

The energy sector dropped 0.2 percent as oil prices edged lower after easing on persistent supply concerns as Russia increased production in July and Saudi Arabia cut the price of crude for its Asian customers.

U.S. crude prices were down 0.5 percent a barrel, while Brent crude was unchanged. [O/R]

Canadian exports shrugged off the effects of U.S. metals tariffs to hit a record high in June, cutting the country's trade deficit to its lowest in 17 months, data showed.

On the TSX, 90 issues were higher, while 139 issues declined for a 1.54-to-1 ratio to the downside, with 8.14 million shares traded.

Top percentage gainer on the TSX were shares of Sierra Wireless, which jumped 16 percent after beating quarterly profit estimate, and Parkland Fuel Co, which rose 8.6 percent after quarterly results.

Dorel Industries fell 4.1 percent, the most on the TSX, followed by shares of Advantage Oil & Gas, down 2.9 percent after quarterly results.

The most heavily traded shares by volume were Aurora Cannabis, Bombardier and Enbridge Inc.

The TSX posted three new 52-week highs and no new lows.

Across all Canadian issues there were eight new 52-week highs and nine new lows, with total volume of 14.56 million shares.

(Reporting by Shreyashi Sanyal in Bengaluru; Editing by Sriraj Kalluvila)