Lopez Obrador's answer marked a pivotal moment after a contentious year of negotiations between the United States, Canada and Mexico to rework the North American Free Trade Agreement (NAFTA), the framework for more than a trillion dollars in annual trade between the three.
Trump called Mexico "great" as the two countries have come to a trade deal agreement.
U.S. Trade Representative Robert Lighthizer, speaking at another event in NY, took aim at Canada's bargaining positions in the two countries' effort to negotiate a new North American Free Trade Agreement.
Canada is facing another US deadline to make a deal: the end of the month.
Hours earlier, in New York, Trudeau gave Canada's NAFTA-talks nemesis a gentle nudge during his own closing news conference that followed the General Assembly.
Later, Trump's other NAFTA partner, Mexico's Enrique Pena Nieto, came by and the USA president stood to shake his hand.
Trudeau also downplayed a brief handshake with Trump at a luncheon Tuesday, where the US president remained seated despite standing to greet other leaders.
QUIZ: Name every player to have played for Liverpool and Chelsea
And Sarri challenged the Belgian forward to take his game further, despite hailing him as the "best technical player" around. He reacted to the strike on Instagram , posting a video of the goal with a caption that revealed his thoughts.
Tropical Storm Kirk forms again Wednesday morning
A hurricane is a tropical cyclone that has maximum sustained surface winds of 74 miles per hour or greater. Kirk is moving to the west at 18 miles per hour and has a minimum central pressure of 1002 mb.
Trump 'fell in LOVE' with Kim Jong-un as they wrote letters
Secretary of State Mike Pompeo met with Ri in NY and is planning to go to Pyongyang next month to continue discussions. Trump began by talking of the massive threat that North Korea posed before he took office in January 2017.
The US trade representative, Robert Lighthizer - Freeland's counterpart at the talks - complained on Tuesday that Canada was not making enough concessions and warned that time was running out. "I think it's important to keep North America together, even if it takes more time" he said. "Frankly, we're thinking of just taxing cars that come in from Canada".
U.S. President Donald Trump said he rejected a meeting with Prime Minister Justin Trudeau over Canada's dairy tariffs, negotiating style and because his people do not like Canada's "representative". "I think our view is now we'll turn to that as a next stage".
Negotiations aimed at a new agreement have been underway for 13 months, but Canada and the US remain at loggerheads.
Speaking separately, Canada's ambassador to Washington said that on a scale of 1 to 10, the chances of an agreement by the Sept 30 deadline were 5.
"We are not getting along with their negotiators", he said.
Canada and Mexico are two of the biggest trading partners with the United States.
Lighthizer also said that the US-Japan trade deal will require congressional approval and will start the process under Trade Promotion Authority (TPA) "fast track" authority. On tariffs, Canada wants protection from so-called Section 232 national security measures the Trump administration has imposed on steel and aluminum imports from Canada and other countries. If Canada comes along now, that would be the best. I've never liked it, it's been very bad for the United States.
Trump then took aim at Canada's dairy supply management system, which he said is hurting Wisconsin dairy farmers by charging them tariffs of up to 300 per cent. "We don't have any comment beyond that".