The Dow Jones Industrial Average index tumbled 1,175 points, or 4.6% to close down at 24,345.75.
The White House moved to reassure investors saying it was focused on "long-term economic fundamentals, which remain exceptionally strong".
Signs of improvement in the economy had driven US markets to record highs.
Ever since he was elected in November 2016 President Donald Trump has tweeted a number of times about the increase in US stock markets, using the gains since he took office to illustrate market improvement.
