SHANGHAI — China’s second-largest maker of telecommunications equipment will not be able to use components made in the United States after the Commerce Department said it failed to punish employees who violated American sanctions against Iran and North Korea.

The ban announced Monday, which effectively locks the company, ZTE Corporation, out of American technology for seven years, is a blow to one of China’s few truly international technology suppliers.

ZTE’s products for the infrastructure of telecommunications networks, as well as its smartphones, use an array of American parts, like microprocessors from the chip maker Qualcomm, glass made by Corning and sound technology from San Francisco-based Dolby.

In a call with reporters on Monday, a senior Commerce Department official said the action was not connected to a broader intellectual property investigation into China.