WEST PALM BEACH, Fla. — President Trump on Wednesday signed tough legislation that would impose sanctions on Chinese and Hong Kong officials responsible for human rights abuses in Hong Kong, expressing support for pro-democracy activists in the territory and most likely angering China as the two countries negotiate ending their trade war.

“I signed these bills out of respect for President Xi, China and the people of Hong Kong,” Mr. Trump said in a statement on Wednesday. “They are being enacted in the hope that leaders and representatives of China and Hong Kong will be able to amicably settle their differences leading to long-term peace and prosperity for all.”

As late as last week, President Trump refused to commit to signing the legislation which Congress had overwhelmingly approved, saying that he supported the protesters but that President Xi Jinping of China was “a friend of mine.”

“I stand with Hong Kong,” he said Friday during a nearly hourlong interview on the morning program “Fox & Friends.” “I stand with freedom. I stand with all of the things we want to do. But we’re also in the process of making the largest trade deal in history.”

The bill would require the State Department to annually review the special autonomous status it grants Hong Kong in trade considerations. That status is separate from the relationship with mainland China, and a revocation of the status would mean less favorable trade conditions between the United States and Hong Kong.

After the Senate approved the bill, the Chinese Foreign Ministry denounced it, saying it “interferes in China’s internal affairs” and “violates the basic norms of international law and international relations.”

The Hong Kong government said the bill was “unnecessary and unwarranted” and would harm relations between the United States and Hong Kong.

Because the bill, in theory, has the support of a veto-proof majority in Congress, it could have been enacted into law even if Mr. Trump had vetoed it.

The bill is the latest sign of a strong bipartisan push in Washington to confront China and its authoritarian leader on a wide range of issues, including commercial practices, global infrastructure building and the detention of at least a million Muslim ethnic minority members in camps in northwest China. Because of the pro-democracy protests, Hong Kong has become a central rallying point.

Senator Ted Cruz, Republican of Texas, and Senator Josh Hawley, Republican of Missouri, both flew to Hong Kong in October, while Speaker Nancy Pelosi, Democrat of California, has met with activists in Washington.

“We have sent a message to President Xi: Your suppression of freedom, whether in Hong Kong, in northwest China or anywhere else, will not stand,” Senator Chuck Schumer of New York, the Democratic leader, said last month. “You cannot be a great leader and you cannot be a great country when you oppose freedom, when you are so brutal to the people of Hong Kong, young and old, who are protesting.”

While there was no immediate reaction from the Chinese government to President Trump’s signing of the bill, Beijing had previously made clear its strong hostility to the measure.

On Monday, China’s foreign ministry summoned the American ambassador to Beijing, Terry Branstad, to criticize the bill. According to the ministry, Zheng Zeguang, a vice foreign minister, demanded that the United States “stop interfering in China’s internal affairs.”

Although Mr. Trump announced last month that the United States and China had reached a “historic” so-called phase one trade agreement, signing a deal has proved elusive. Both the United States and China have tried to keep the Hong Kong issue separate from their bilateral trade talks. The commerce ministry issued a statement earlier this week that talks were going well on a partial resolution of the issues

Eswar Prasad, the former head of the International Monetary Fund’s China division, said the injection of Hong Kong into the trade process could derail the talks with China, which is notoriously sensitive about outside political interference.

“The legislation will further fuel the narrative in Chinese domestic policy circles that the U.S. is attempting to infringe on the sovereignty of China in terms of its internal economic and political affairs,” Mr. Prasad said.

Economists at Goldman Sachs said in a note to clients this month that the Hong Kong legislation was a potential “complication,” warning that China’s Ministry of Foreign Affairs had promised “strong countermeasures” if such a bill were enacted.

On Tuesday, Secretary of State Mike Pompeo said the Trump administration “has been pretty clear about our expectations about how Beijing will treat people throughout their country.”

“We have human rights standards that we apply all across the world, and Hong Kong is no different,” Mr. Pompeo told reporters.

He appeared to be goading Beijing, suggesting that the degree of independence Hong Kong maintains as part of its “one country, two systems” agreement with China was weakening.

“Our support for the Chinese Communist Party’s continued commitment to the promises that they made remains unwavering,” Mr. Pompeo said. “And I think you saw that from the people of Hong Kong this past week. That’s what they’re asking for, too.”

Pro-democracy candidates overwhelmingly won local elections in Hong Kong this weekend, shocking Beijing and its allies in Hong Kong’s government. Smarting from the loss, Chinese officials have accused the United States of interfering in the election.

Keith Bradsher contributed reporting from Shanghai.