After US stocks plummeted on Monday, the White House sought to play down concerns, saying President Donald Trump was focused on "exceptionally strong" underlying fundamentals in the economy.

White House spokeswoman Sarah Sanders said the economy was experiencing "strengthening U.S. economic growth, historically low unemployment, and increasing wages for American workers."

But Trump himself did not comment on the market, even as share prices sold off dramatically while he was touting the economy and last year's tax cuts in a speech in Ohio.

That was a contrast to recent months when Trump has often talked about stocks, taking credit for the rally the market enjoyed during 2017 and the first few weeks of this year.

It was a sign that Trump may be absorbing a tough message, underscored by former White House advisers, that American presidents traditionally have avoided commenting directly on Wall Street's fickle trends.