Clinton said the U.S. must also underscore its commitments to both Britain and Europe.

In response to the decision, Clinton issued several tweets, the first of which said, "We respect the choice the people of the United Kingdom have made".

US President Barack Obama, during a visit to London in April, had argued passionately against a British exit.

Clinton, Obama's former secretary of state, had said in the past that she hoped the UK would stay in the EU, Reuters reports.

"This time of uncertainty only underscores the need for calm, steady, experienced leadership in the White House," Clinton also posted on Twitter.

Presumptive Democratic presidential candidate Hillary Clinton said the United States must first safeguard against any economic fallout at home at "this time of uncertainty" in a message on Twitter on Friday (June 24) after Britain decided it would leave the European Union.

Her likely Republican rival for the White House, Donald Trump, has applauded the British decision to leave the EU.

Britain's decision to leave the EU has forced the resignation of Prime Minister David Cameron and dealt the biggest blow to the European project of greater unity since World War Two.

The decision was met with watchful acceptance by U.S. officials even as it rattled Wall Street and other markets around the world.

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