The White House said Monday it is worried about the U.S. stock market sell-off.

"We're always concerned when the market loses any value, but we're also confident in the economy's fundamentals," an official said in a statement to CNBC Monday morning.

After Monday's market close, the White House said that President Donald Trump is focused on the country's "long-term economic fundamentals, which remain exceptionally strong."

The Dow Jones industrial average briefly fell more than 1,500 points before closing 1,175 points lower, or down 4.6 percent. The S&P 500 erased its gains for the year and closed 4.1 percent lower. Stocks fell Friday and posted their worst week in two years.

Earlier in the afternoon, White House spokesman Raj Shah said "markets do fluctuate. Short-term we all know that." He was traveling on Air Force One with the president to Ohio.

Shah added the "fundamentals of the economy are strong," referencing evidence of wage growth and unemployment numbers at their lowest in nearly two decades.

Trump has touted the strong stock market performance since his election win and has yet to deal with a significant market pullback. The Dow remains more than 30 percent higher since the election.

— With reporting by CNBC's Eamon Javers.