And the final decision may not be entirely clear-cut: Aides were still deliberating on "caveats in the language", one official said.
For his part, Trump tweeted only that he would be announcing his decision regarding the treaty "over the next few days".
Tesla is one of hundreds of companies that has asked Trump not to withdraw. Trump is to meet Wednesday with Secretary of State Rex Tillerson, who believes the USA should stay in so it can keep its place at the worldwide bargaining table. Chief strategist Steve Bannon supports an exit.
If Trump withdraws from the historic pact, the USA would be one of just three nations not part of the global initiative to reduce planet-warming emissions.
Guterres said he will also rally countries to raise the bar on efforts to limit temperature rise and the United Nations system to promote climate action.
The official is involved in preparing the meeting between EU Council President Donald Tusk, Juncker and Chinese Premier Li Keqiang, but can't speak on the record because their meeting statement wasn't finalized.
Under former President Barack Obama, the USA had agreed under the accord to reduce polluting emissions by about 1.6 billion tons by 2025.
World leaders repeatedly pressed Trump on the issue during his recent trip to Europe, as did Pope Francis, who gave the president his papal encyclical on climate change when they met in the Vatican.
President Trump has been making good on his promises to undo regulations set by his predecessor.
In or out? Trump announcing decision on global climate pact
Trump was responding to questions from reporters about whether he plans to withdraw the US from the landmark global agreement. President Donald Trump is likely to withdraw the nation from the Paris Agreement on climate change, local media reports said.
"This is a decision that will cede America's role internationally to nations like China and India, which will benefit handsomely from embracing the booming clean energy economy while Trump seeks to drive our country back into the 19th century", Brune wrote. While a shift of focus back onto fossil fuels will undoubtedly provide jobs growth in the short-term, whether the president believes in climate change or not, the future of energy is in renewables.
"Generations from now, Americans will look back at Donald Trump's decision to leave the Paris Agreement as one of the most ignorant and risky actions ever taken by any President", Sierra Club executive director Michael Brune said in a statement.
The House Democratic leader, Rep. Nancy Pelosi of California, referred to it as "a stunning abdication of American leadership and a grave threat to our planet's future".
That's what the top House Democrat is calling President Donald Trump's expected decision to pull the USA from a historic climate agreement. Such an assertion stands in defiance of broad scientific consensus.
But Cohn, Trump's chief White House economic adviser, told reporters during the trip overseas that the president's views on climate change were "evolving" following the discussions with European leaders.
Since taking office, Trump and Pruitt have moved to delay or roll back federal regulations limiting greenhouse gas emissions while pledging to revive long-struggling United States coal mines.
Mr Trump said the USA would withdraw from the Paris Agreement, secured in the French capital in December 2015, which commits countries to curbing rising global temperatures.
"Pulling out of Paris is the biggest thing Trump could do to unravel Obama's climate legacy". McKenna says the Canadian government remains committed to the Paris Accord amid.
The decision to withdraw from the climate accord was influenced by a letter from 22 Republican US senators, including Majority Leader Mitch McConnell, calling for an exit, Axios reported. They include Apple, Google and Walmart.