As Russia was unleashing its deadliest attack on Ukraine’s capital in nearly a year, President Volodymyr Zelensky arrived in the Canadian Rocky Mountains early Tuesday hoping to meet with President Trump and secure more support for Ukraine from the Group of 7 industrialized nations.

Instead, Mr. Trump left the global powers’ summit early, canceled his meeting with Mr. Zelensky, lamented Russia’s absence from the leaders’ get-together and rejected the idea of issuing a joint statement in support of Ukraine.

A single, brief reference to Ukraine in a summary of the talks’ conclusions, released by the host, Prime Minister Mark Carney of Canada, backed Mr. Trump’s peacemaking efforts and did not directly criticize Russia, though it said the leaders would explore ways to bring more pressure to bear on Moscow.

At a news conference at the end of the summit in Kananaskis, a scenic mountain resort in western Canada, on Tuesday evening, Mr. Carney said that several of the Group of 7 nations would have preferred stronger language on Ukraine.

“There would be things that some of us, Canada included, would say above and beyond what was said in the chair summary,” he said, referring to his own statement.

Instead, Mr. Carney said, he had chosen to focus on securing a joint statement with the other leaders on the escalating crisis in the Middle East. “Given the exceptional, fast-moving situation in Iran, we concentrated on that,” he said.