BEIJING—Chinese President Xi Jinping outlined an updated vision for China’s future as an internet and technology power, pledging more state support for sectors caught in the crosshairs of a trade fight with the U.S.

Speaking at a two-day conclave on cyberspace that ended Saturday, Mr. Xi called on officials, enterprises and researchers to redouble already extensive national efforts to achieve breakthroughs in “core technologies” like semiconductors—an area where China still lags behind the U.S.

The development of new information technologies “presents the Chinese people with an opportunity you rarely see in a thousand years,” Mr. Xi said, according to an account of his speech published by the official Xinhua News Agency. “We must keenly seize the historic opportunity.”

Mr. Xi’s speech echoes themes made in a landmark address in 2016 in which he set out a blueprint for China to become an “internet superpower.” His remarks this year come as technology has emerged at the center of escalating trade disputes between China and the U.S. that has also ensnared trade in Chinese steel and aluminum and U.S. sorghum.

Earlier this week, the U.S. banned American businesses from supplying technology and services to Chinese telecom equipment giant ZTE Corp. for violating a year-old agreement after the company admitted to disregarding sanctions and selling gear to Iran and other countries.