WASHINGTON - Microsoft said on Sunday that it would continue to pursue acquiring TikTok after consulting with President Trump, who seemed to be backing off a pledge to ban the app.

The announcement came as Mr. Trump has expressed repeated concerns about TikTok and concerns around national security in recent weeks.

On Friday, Mr. Trump threatened to ban the app entirely within the United States.

Those plans appeared to change after Satya Nadella, the chief executive of Microsoft, spoke over the weekend with the president, assuaging his worries over the safety of the app.

The latest move may clear the way for a potential blockbuster deal between the software giant and the viral social media phenomenon.

Microsoft said it would pursue the deal over the coming weeks, and expected to complete the discussions no later than Sept. 15. Such a deal would involve purchasing the TikTok service in the United States, Canada, Australia and New Zealand; ByteDance, the parent company of TikTok, would continue to own the social media app’s operations in Beijing and other markets.