WASHINGTON — The Treasury Department officially declined on Friday to label China a currency manipulator, breaking one of President Trump’s most prominent campaign promises.

In its exchange rate report to Congress, the Treasury said that in spite of China’s large trade surplus with the United States, it was not acting improperly to depress the value of its currency.

Mr. Trump signaled this week in an interview that he was reversing his position, and he has taken a less confrontational stance toward China since meeting with President Xi Jinping this month.

The report did take a more pointed tone toward China than in previous years, calling on Beijing to act to reduce trade imbalances and open its markets to American goods and services. It also said that the United States remained poised to act if China did start to meddle with its currency, as it did in the not-too-distant past.