It remained unclear on Friday night whether a joint statement, if one is issued, would result in a clear commitment by the United States to stay in the accord, or a vague message leaving open the possibility that Mr. Trump could still decide to end American participation in the global agreement.

Andrew Light, who was a senior climate change adviser at the State Department under President Barack Obama, said the other leaders at the summit meeting — representing the G7 members Canada, France, Germany, Italy, Japan and the United Kingdom, along with the European Union — would go home frustrated “if Trump blows this thing up and continues to sit on the fence.”

The other leaders confronted Mr. Trump on climate change as soon as he arrived in Europe. White House officials said Emmanuel Macron, the French president, brought the subject up during NATO meetings in Brussels, as did Charles Michel, the Belgian prime minister. In Sicily, White House officials braced for what they knew would be “a robust discussion” of the issue.

The lobbying continued throughout the day on Friday, as the leaders gathered behind closed doors for a series of meetings, luncheons and a dinner, taking a break for an evening concert in the Teatro Antico di Taormina, an ancient amphitheater overlooking the Mediterranean Sea.

During one extended discussion on Friday, Mr. Trump listened to the pleas of the other leaders, White House officials said, but reiterated that the environment and jobs were both important to him. He talked about environmental awards he had received and declined to say when he would make a decision on the Paris agreement.

“I want to get to the right decision,” Mr. Trump told the group, according to Mr. Cohn.

The other leaders were said to be wary of how they spoke to the American president, concerned that they could anger him easily, which could result in his deciding to pull the United States out of the Paris agreement after he returns home.

“They are all trying to figure out how do you offer convincing arguments to Trump without him feeling that you are ganging up on him,” said Alden Meyer, the director of strategy and policy for the Union of Concerned Scientists, an advocacy group.