BEIJING — Sounding confident after a burst of high-profile diplomacy, President Xi Jinping told Communist Party officials in a major address here over the weekend that China would be nice to its neighbors in Asia but that he would run an active foreign policy and be relentless in promoting China’s rejuvenation onto the global stage.

Mr. Xi did not mention the United States by name but took an unmistakable jab at Washington, saying, “The growing trend toward a multipolar world will not change,” a reference to the Chinese view that America’s post-Cold War role as the sole superpower is drawing to a close.

China now had the power, he added, to steer world crises and turn them to China’s advantage, a declaration, analysts said, of how Mr. Xi sees China’s growing pre-eminence.

This is the second time that Mr. Xi has spoken to the leadership in public about foreign policy — he did so a year ago — but his speech on Saturday, televised by the state broadcaster, CCTV, was more emphatic and sweeping, analysts said.