The French president was speaking alongside the Canadian prime minister, Justin Trudeau, who is hosting the G7 summit in Quebec amid sharp disagreements between the United States president and the six other leaders of industrialized liberal democracies over trade, climate change and the nuclear deal with Iran.
The two leaders also dismissed as absurd Trump's assertion of national security concerns.
"There's no question that on trade, on climate change, on some other issues there will be differences of perspective", he said.
The Prime Minister's Office says the two men also signed a joint statement on multilateralism that "reaffirmed the strong ties between Canada and France, as well as their commitment to shared values like liberty, democracy, respect for human rights, and the rule of law".
"We know there will certainly be frank and at times hard conversations around the G7 table, particularly with the American president on trade, on tariffs", he said. "It will start first of all to hurt USA workers, and the cost of raw materials will rise, and industries will become less competitive", he said.
Whether or not Trump attends the G7 meeting, the spectre of the president's belligerent trade policy will linger over the gathering.
So great is the rift between traditional allies that some observers have suggested renaming the G7 summit the G6+1 - and Macron said they should not hesitate to reach agreements without Trump.
And he made a public plea that Trump not try to frustrate efforts by France and others - even if he disagrees with the approach taken - to engage Iran on halting its nuclear weapons development program.
Canada's non-American G7 partners don't envy Trudeau, and some are downright sympathetic.
Trudeau and Trump may lock horns again in La Malbaie, Que., where the prime minister will host the G7 summit June 8 and 9.
"A trade war doesn't spare anyone", he said.
Both Trudeau and Macron emphasised the importance of dialogue and courtesy at the summit, which begins on Friday.
The summit has already been dubbed the "G6 plus one" due to Mr Trump's isolation over trade and his decision to pull the United States out of the Iran nuclear deal.
For his part, Macron talked about Canada's military contributions to support French operations in Mali and their shared interests in the culture and arts.