A dive in oil prices sent stock markets lower after producers failed to agree on a plan to curb global supply. However, falls on European markets eased and Wall Street opened only modestly lower.
US crude prices were down 4.34 percent to $38.61 a barrel.
China reported slower-than-expected first-quarter seasonally adjusted growth, adding to headwinds for Canada's risk-sensitive commodity-linked currency.
Foreign investors bought a net C$15.94 billion ($12.36 billion) in Canadian securities in February, mainly in bonds, Statistics Canada said.
Bank of Canada Governor Stephen Poloz pushed back on Saturday at the suggestion the central bank had accepted economic assumptions from the Department of Finance without doing due diligence about Finance Minister Bill Morneau's budget.
At 9:35 a.m. EDT (1335 GMT), the Canadian dollar was trading at C$1.2885 to the greenback, or 77.61 US cents, weaker than Friday's close of C$1.2837, or 77.90 US cents.
The currency's strongest level of the session was C$1.2862, while it touched its weakest since April 11 at C$1.2990.
The loonie hit a nearly nine-month high at C$1.2744 last week. However, the central bank warned the same day that the country's improving economy faced downside risks, including a stronger currency that could drag on non-commodity exports.
Still, the overnight index swaps market has moved to imply a slight probability of a Bank of Canada interest rate hike this year after having implied a more than 50 percent probability of a cut at the start of March.
Speculators have increased bullish bets on the loonie, Commodity Futures Trading Commission data showed on Friday.
Net long Canadian dollar positions rose to 2,385 contracts in the week ended April 12 from 97 contracts the prior week. At the end of January, net short exposure was the highest in five months at 66,819 contracts.
Canadian government bond prices were slightly lower across the maturity curve, with the two-year price down 0.5 Canadian cent to yield 0.595 percent and the benchmark 10-year falling 5 Canadian cents to yield 1.276 percent.
The Canada-US 10-year spread was 1 basis point more negative at -49.1 basis points as US Treasuries underperformed. On Friday, it touched its smallest gap in 10 months at -48.1 basis points.