The loonie was down 0.19 of a cent to 99.29 cents US.
The ECB decided against taking immediate action to attack the continent's debt crisis, as Mario Draghi dashed earlier hopes that significant steps would be made.
A week ago, Draghi promised to do "whatever it takes" to preserve the euro.
Afterwards, the euro lost ground against the U.S. dollar.
"It looks like the ECB was caught off guard by Draghi's verbal intervention last week, and while there was a consensus that action was needed to address soaring borrowing costs for peripheral countries, there wasn’t time to come to decisions on how that should be done," said CIBC chief economist Avery Shenfeld in a note.
"We expect that by September, the ECB will be in a better position to announce the details."
In commodities, the September crude contract on the New York Mercantile Exchange closed $1.78 lower to US$87.13 a barrel.
December gold fell $16.60 to close at US$1,590.70 an ounce while September copper moved down 8.4 cents to US$3.29 a pound.
In U.S. data, more people applied for U.S. unemployment benefits last week, though the data was likely skewed higher by seasonal factors.
Weekly applications increased by 8,000 to a seasonally adjusted 365,000, the Labor Department said Thursday. The four-week average, a less volatile measure, fell for the sixth straight week to 365,500, the lowest since March 31.