SHANGHAI — The Chinese government on Thursday said Beijing and the Trump administration had agreed to get rid of some tariffs as the two sides work toward ending their 19-month trade war.

But Beijing also hardened its stance in insisting that no deal could take place without each side canceling at least some tariffs.

Gao Feng, a spokesman for China’s Commerce Ministry, said at his weekly news conference in Beijing that the United States had agreed that any deal would have to include tariff reductions by both sides.

“In the past two weeks, the leaders of the two sides have conducted a serious and constructive discussion on properly addressing the concerns of both sides, and agreed to cancel the tariffs by stages in accordance with the development of the agreement,” he said.

Mr. Gao did not specify what tariffs might be dropped, or when. American officials have already been considering for weeks whether to drop the last round of tariffs that President Trump had imposed on Chinese goods on Sept. 1, which fell more heavily on consumer goods than previous tariffs. However, some Trump administration advisers have opposed dropping tariffs.

China will insist that any deal include canceling some tariffs, Mr. Gao said.

“If China and the United States reach the first phase agreement, according to the content of the agreement both sides should cancel added tariffs at the same time with the same proportion,” he said. “This is an important condition for reaching an agreement.”

The news conference occurred in the middle of the night Washington time, and there was no immediate response from the Office of the United States Trade Representative, which is leading the American side of the negotiations.

Mr. Gao did not say whether it would be enough for President Trump to abandon tariffs he had threatened to impose so as to pressure China into reaching a deal. Mr. Trump had threatened to impose higher tariffs in October and again in December. But he called off the first increase after announcing a so-called phase one deal on Oct. 11. The details of that deal are still being worked out.

The trade war between the world’s two biggest economies has been taking an increasing toll on both sides. Since the start of the trade war, the United States has imposed tariffs on more than $360 billion a year worth of Chinese products, while China has placed tariffs on roughly $100 billion of American goods. Tariffs now cover about two-thirds of the trade in goods in each direction.

The trade war has contributed to a slowdown in China’s economic growth, while economists have increasingly warned of the potential impact on the United States.

Mr. Gao’s public demand for the cancellation of tariffs marked a subtle shift from his previous comments, which were somewhat less specific on what China required to reach any interim agreements.

The news conference on Thursday represented the first official comments on the trade war since the conclusion a week ago of the first meeting in 20 months of the Chinese Communist Party’s Central Committee, a group of senior leaders. In the past, Beijing’s position has shifted away from compromise after a broader array of Communist Party officials were briefed on progress in the trade talks.

The United States and China were close to a deal in early May. But when the draft agreement was broadly distributed within the Chinese leadership, its contents sparked worries about the extent of China’s concessions. China’s trade negotiators quickly demanded extensive changes in the agreement.

Communist Party officials based outside of Beijing have a history of skepticism toward compromises with the United States on trade. Chen Deming, a Chinese commerce minister who was perceived by some midlevel officials as too conciliatory, unexpectedly lost his seat on the Central Committee in voting at the Communist Party Congress in 2012.

Chinese officials last month had also pursued a compromise so as to resume buying American farm goods, which China needs after a devastating outbreak of African swine fever has killed a large share of the country’s pigs, the country’s main source of protein. Some purchases have resumed following the compromise, leaving the Chinese side free to focus on the details of an accord.

Vice Premier Liu He, China’s chief negotiator in the trade talks with the United States, had said in May that there would be no deal without a complete elimination of American tariffs. Mr. Gao’s remarks on Thursday represented a refinement of that stance, as he said that there could be partial deals along the way as long as they also canceled some tariffs as well.