Trudeau and Trump are due to meet on Friday "and they will have lots to talk about", the official added.
Trump is said to bristle at the British Prime Minister's phone calls, as May launches into policy detail rather than broader conversation.
Macron called on other G7 leaders not to water down a joint communique at the end of the summit, at the expense of shared values, simply in an effort to win Trump's signature, warning that a "G6 plus one" outcome was possible. He added at Parliament Hill in Ottawa on Thursday that Trump's economic move is putting American jobs "on the line" too. "The impact on Canada and ultimately on workers in the US won't be a laughing matter".
At stake is the risk of tit-for-tat tariffs between the major western economies turning into an unrestrained trade war. "The cost of raw materials will rise and industry will become less competitive".
Canadian Prime Minister Justin Trudeau's position on the punitive measures would remain "consistent and clear" during talks at the summit, the official said.
"The president will travel directly to Singapore from Canada in anticipation of his upcoming meeting with North Korea's leader Kim Jong Un Tuesday".
Leaked images show the Blackberry Key2
There's nothing left to the imagination as images, price and specifications leak ahead of the BlackBerry KEY2 launch tomorrow. Canadian firm BlackBerry had recently revealed that it will launch its new smartphone KEY2 on June 7 at NY city.
One source with knowledge of the matter said that Italy wanted to "create as much space as possible to continue the dialogue with the USA", noting that new Italian Prime Minister Guiseppe Conte, a political novice, would be treading carefully in Canada because he "needs to see the dynamics of the group".
Last night she called from restraint from the European Union, which is set to unveil its own list of tariffs on USA exports in retaliation.
Trump's attitude towards the global summit is already causing some reaction online.
Trump threatened to escalate a trade war with the European Union and Canada the night before he meets their leaders at the G7 summit.
These sentiments were echoed by his boss, German Chancellor Angela Merkel, when asked on Wednesday how she would deal with Trump in Canada.
May and Trump also clashed recently over other issues, such as Trump tweeting videos of the far-right Britain First group, and relocating the US Embassy in Israel from Tel Aviv to Jerusalem.
President Trump and French President Emmanuel Macron participate in a state arrival ceremony at the South Lawn of the White House on April 24, 2018.
He is planning to leave the summit early on Saturday morning before the leaders' scheduled meetings are completed, said Canadian government officials.