The pause was "based on the fact that Canada and the U.S.A., subject to the finalisation of documents, have a DEAL," Trump said in a post on Truth Social.
There was no immediate comment or confirmation from the Canadian government.
Trump added in his social media post the Keystone XL Pipeline - a project cancelled by former President Joe Biden in 2021 after years of indigenous and environmental opposition - "may be awoken from the grave," but did not provide details.
Trump's post came after he spoke with Canadian Prime Minister Mark Carney on Tuesday, their second conversation this week, and after weeks of intense, opaque negotiations.
Existing US auto tariffs had been a sticking point, two industry sources familiar with the talks said earlier.
The new US tariffs would have covered about $US20 billion worth of imports and applied regardless of whether Canadian goods qualify for preferential treatment under the US-Mexico-Canada trade agreement, which has shielded much of Canadian industry from earlier US tariffs.
Trade experts and industry officials say new tariffs could lead to job losses and business closures in vulnerable sectors, including lumber, wine and dairy.
They also warn the dispute could complicate broader USMCA negotiations.
"There are billions in goods per year that were not impacted before, but now are at risk of being impacted significantly," said Candace Laing, CEO of the Canadian Chamber of Commerce.
"Business have been doing a high-wire act for well over a year, holding off on hiring, investment and growing in Canada," she said.
Canada's minister responsible for US trade, Dominic LeBlanc, and chief trade negotiator Janice Charette have been in Washington since last week for talks.
On Monday, the Canadian officials met for nearly two hours with US Trade Representative Jamieson Greer and Commerce Secretary Howard Lutnick.
Greer has repeatedly cited Canada's tariffs that followed initial US tariffs, some provinces' refusal to stock US liquor and Canada's dairy supply management system among US grievances.
Two sources said one of the main sticking points was US tariffs on Canadian vehicles.
The sides have discussed cutting US Section 232 tariffs on Canadian vehicles to 15 per cent from 25 per cent, with further reductions based on the amount of US content in each vehicle, the sources said.
The details of the deal touted by Trump remained unclear.
A major point of contention was how tariff deductions based on content should be calculated, with Washington demanding that only US-produced content be counted. Canada pushed for all North American content, including Canadian and Mexican parts, to be counted, the sources said.
Earlier on Tuesday, the US Commerce Department released new rules for automakers exporting from Canada and Mexico to certify their current levels of US content for tariff deductions, reducing the complicated exercise to once per year from twice.
But the Federal Register notice said automakers must re-certify vehicles' American content by September 30 for them to claim deductions in the new annual cycle starting December 1.
