ST. PETERSBURG, Russia — The president of France spoke of an “erroneous decision.” Japan’s Prime Minister lamented disruptions to trade. The head of the International Monetary Fund said recent foreign policy positions were “not the right way to go.”

They were not criticizing President Vladimir V. Putin of Russia, whom the United States has tried to isolate on the world stage.

Instead, Mr. Putin sat, nodding approvingly, on a stage beside these heads of state and other senior officials at a business forum that veered into what sounded at times like a group-therapy session for world leaders slighted by President Trump.

Speaking to an auditorium of business executives, President Emmanuel Macron of France said he had tried to persuade President Trump to remain in the international climate accord, observe a nuclear deal with Iran and refrain from moving the United States embassy in Israel to Jerusalem, only to be rebuffed on all three points. Mr. Macron called the embassy move “erroneous.”