SAN FRANCISCO — Kevin Mayer, the chief executive of the Chinese-owned video app TikTok, said on Wednesday that he was resigning after the company came under sustained pressure from the Trump administration over its ties to China.
In a note to employees, which was reviewed by The New York Times, Mr. Mayer said a series of changes to TikTok’s structure had prompted him to leave. The app, which is owned by the Chinese internet company ByteDance, has been ordered by the White House to sell its U.S. operations by mid-September. Mr. Mayer, 58, did not address the specific timing of his departure.
“In recent weeks, as the political environment has sharply changed, I have done significant reflection on what the corporate structural changes will require, and what it means for the global role I signed up for,” he wrote in the email. “Against this backdrop, and as we expect to reach a resolution very soon, it is with a heavy heart that I wanted to let you all know that I have decided to leave the company.”
Mr. Mayer, who announced in May that he would join TikTok, added that he had signed up for a global role and that leading a global team had been a “big draw” for him.
His departure underscores the difficulties facing TikTok as it has become a geopolitical piñata amid worsening U.S.-China tensions. As part of a campaign of being tough on China, President Trump and other White House officials have zeroed in on technology companies, which they say are beholden to the Chinese government through security laws. In recent months, the Trump administration has stepped up its scrutiny of TikTok, saying it poses just such a national security threat because of its Chinese ownership.
This month, Mr. Trump signed an executive order to block TikTok if ByteDance did not sell the app’s U.S. operations within 45 days. He later issued another executive order giving ByteDance 90 days to close such a deal.
The White House’s moves have pushed ByteDance and TikTok to seek a buyer for the app’s U.S. operations. U.S. tech giants such as Microsoft and the enterprise software maker Oracle, along with other bidders, have been discussing a potential deal, with prices ranging from $20 billion to $50 billion. But talks are fluid, people with knowledge of the discussions have said, and no deal may be reached.
At the same time, TikTok has pushed back against the Trump administration. On Monday, the company sued the U.S. government, accusing it of depriving it of due process by forcing a sale using an executive order.
Zhang Yiming, the founder and chief executive of ByteDance, said in a note on Wednesday to employees that Mr. Mayer had joined the company at “arguably our most challenging moment.” He said that he and Mr. Mayer had spoken and that he understood how Mr. Mayer’s global role would be affected given that he was based in the United States.
Mr. Zhang added that ByteDance and TikTok were moving swiftly to resolve its issues in the United States and India, where the app was banned in June. “I cannot get into details at this point, but I can assure you that we are developing solutions that will be in the interest of users, creators, partners and employees,” he said.
In a statement, TikTok said, “We appreciate that the political dynamics of the last few months have significantly changed what the scope of Kevin’s role would be going forward, and fully respect his decision.”
Vanessa Pappas, general manager of TikTok in North America, will take over as the interim global head of the company.
The White House did not immediately respond to a request for comment. The Financial Times earlier reported Mr. Mayer’s resignation.
Mr. Mayer, who was the top streaming executive at Walt Disney Company, joined TikTok in May not only as its chief executive but also as the chief operating officer of ByteDance. In an interview at the time, Mr. Mayer said he had left Disney for TikTok because “the magnitude of this opportunity was just something I couldn’t pass up.”
TikTok has become increasingly popular in the United States and in other countries like India, where teenagers and young adults use it to create and share videos. In the United States alone, TikTok has said, it has more than 100 million users. In total, TikTok’s app has been downloaded about 1.9 billion times worldwide, according to Sensor Tower, an app data firm.
Mr. Mayer’s hiring was part of an effort by TikTok to bring on more American executives as Washington’s scrutiny of the app grew. TikTok also hired more employees in Los Angeles, New York and more than a dozen other places in the United States. The company has said it planned to add over 10,000 new jobs in the country.
But things changed drastically shortly after Mr. Mayer joined TikTok, with White House pressure ramping up and then the signing of the executive orders this month.
Officials at TikTok were shocked by the orders, people with knowledge of the situation have said. For months, the company had worked to satisfy the White House by holding talks with investors and others to reduce its Chinese ownership and to find a way to store data on its American users in the United States. TikTok has said it currently stores U.S. user data on servers in Virginia and Singapore.
In its fight to stay alive in the United States, TikTok also pointed to Mr. Mayer’s status as an American executive based in the country to argue that it was not beholden to the Chinese government. It made the argument both in recent communications with lawmakers on Capitol Hill and in the lawsuit it filed on Monday against the Trump administration.
In his note to employees on Wednesday, Mr. Mayer indicated that “the future is incredibly bright” for TikTok.
Alluding to the political criticism, he said, “Like all companies in our space, we face challenges, but I have tremendous confidence that we have a world-class security team in place working to make people on our platform safe, and an amazing global team that makes this such a unique, creative and inclusive platform.”
Raymond Zhong contributed reporting from Taiwan.