The Canadian dollar inched up 0.04 cents to 77.95 cents U.S.
The Standard & Poor's 500 index dropped 41 points, or 1.5 percent, to 2,671.
The administration has said duties would protect USA companies, but critics say they would raise costs for industry and fail to deliver on a Trump campaign pledge to boost domestic jobs.
Trump told industry executives Thursday he would impose the tariffs next week.
Federal Reserve Chairman Jerome Powell said on Thursday there was no evidence the US economy is overheating, and labor markets may still have room to improve as the central bank sticks with a gradual pace of interest rate increases.
While Powell tried to temper remarks he made on Tuesday that raised concerns about the potential for four interest rate hikes this year rather than the Fed's forecast of three, Dudley was a bit more pointed and said four rate hikes would be "gradual".
The price data "will add to the sense that the weak patch in inflation is behind us", and "barring some kind of disaster, a March hike is pretty much a done deal", Feroli said.
"I think the industrials are down as they use a lot of steel, and the uncertainty of what the tariff announcement could mean for them", said Ryan Detrick, Senior Market Strategist for LPL Financial.
"This is sort of working your way into a trade war which is a drag on the economy".
Detrick also said that investors were anxious about retaliatory tariffs from China.
UN Aid Chief: Syria Cease-Fire Yet to Be Implemented
Security Council was told Wednesday that nothing has changed, particularly in the besieged Damascus suburb of Eastern Ghouta. Meanwhile, the Britain-based Syrian Observatory for Human Rights reported more fighting Wednesday in eastern Ghouta.
But the euro has recovered to trade up 0.5 percent at $1.2254.
The British pound slipped 0.1 percent to $1.3749.
One of the key aspects of Powell's question-time comments was his view on the "continuing strength in the labour market".
The Dow Jones industrial average fell 420 points, or 1.7 percent, to 24,608.
Gold prices steadied on Wednesday after the previous session's more than 1 per cent fall following comments by the Federal Reserve's new chairman that fueled views the United States central bank would raise rates four times this year rather than three.
The MSCI All-Country World Index declined 0.5 percent.
Bond prices rose. The yield on the 10-year Treasury fell to 2.80 percent. Some also pointed out that support for the dollar from higher interest rates - the main driver of its gains until early 2017- has been tenuous in the past year, as investors´ focus is shifting to Washington´s currency policy and the twin USA trade and fiscal deficits.
But the Bank of Japan and European Central Bank could act as counterweights - euro zone inflation for February at 1.2 per cent showed on Wednesday that the ECB's near-2-per cent target remains years away. "The things we don't want to have happen is to get behind the curve, have inflation move up and have to raise rates too quickly and cause a recession", Powell said. But raising interest rates to fight inflation makes the non-yielding metal less attractive.
Spot gold is expected to break support at US$1,317 per ounce and fall to the next support level at US$1,303, as suggested by its wave pattern and a projection analysis, Reuters technical analyst Wang Tao said. Brent crude, the worldwide standard, lost $1.04 to $63.70 per barrel.