WASHINGTON — A White House economic analysis of President Trump’s trade agenda has concluded that Mr. Trump’s tariffs will hurt economic growth in the United States, according to several people familiar with the research.

The findings from the White House Council of Economic Advisers have been circulated only internally and not publicly released, as is often the case with the council’s work, making the exact economic projections unknown. But the determination comes as top White House officials continue to insist publicly that Mr. Trump’s trade approach will be “massively good for the U.S. economy.”

The chairman of the Council of Economic Advisers, Kevin Hassett, an economist who came to the administration from the American Enterprise Institute, a conservative think tank, dodged questions at a White House briefing on Tuesday about whether tariffs would hurt an economy that has accelerated during Mr. Trump’s tenure.

Asked whether the administration’s economists had modeled the impact that a trade war with China would have on the United States economy, Mr. Hassett said Mr. Trump was a great negotiator who would persuade other countries to open their markets to American products.