President Trump won’t decide on U.S. participation in the Paris climate-change agreement until he returns from Europe, but a top adviser suggested Thursday the president is eyeing lower U.S. emissions targets as the price for remaining in the pact.

White House national economic council director Gary Cohn said the argument “that’s probably the most persuasive” for Mr. Trump is that emissions levels negotiated by former President Barack Obama “would be constraining to our economic growth.”

While cautioning reporters not to “read too much into this,” Mr. Cohn said “we know that the levels that were agreed to by the prior administration would be highly crippling to the U.S. economic growth.”

The agreement signed by Mr. Obama in December 2015 requires the U.S. to cut its greenhouse gas emissions at least 26 percent by 2025.

When all factors are considered, Mr. Cohn said, “growing our economy is going to win.”

“The president ran on growing our economy,” he said.

Mr. Cohn made his comments to reporters aboard Air Force One as Mr. Trump flew to Taormina, Sicily, for the G7 Summit that begins Friday. The leaders of the other G7 industrial nations — Japan, Canada, Britain, France, Germany and Italy — are all expected to lobby Mr. Trump about the dangers of climate change and the importance of the U.S. remaining in the Paris agreement.

During his election campaign, Mr. Trump pledged to pull the U.S. out of the Paris deal. But since taking office, the president has postponed a decision as top advisers debate the merits of such a move.

The president has heard from business leaders on both sides.

“We’ve heard from every business that’s come to the White House that we’ve got to get better jobs,” Mr. Cohn said. “We’ve got to get rid of regulation that’s hindering growth. We’ve got to improve taxes. We’ve got to improve our infrastructure.”

But he added, “He wants to do the right thing for the environment. He cares about the environment. But he also cares very much about creating jobs for American workers. He wants to hear what the Europeans have to say about that.”

During a NATO meeting in Brussels, Belgium, on Thursday, several European leaders lobbied the president on staying in the Paris agreement.

Mr. Cohn said the G7 Summit is a “time for him to have an intimate discussion and understand their issues, but more importantly for them to understand our issues.”

“Our issues of, we’ve got to get the American economy growing again, we’ve got to get American workers back into better jobs, we’ve got to grow the middle class,” he said.