President Donald Trump reacts as he walks with the President of the European Council Donald Tusk (not pictured) after a meeting in Brussels, Belgium, May 25, 2017.

The greenback fell Wednesday after President Donald Trump said in a tweet that the U.S. should match China and Europe's "currency manipulation game."

"China and Europe playing big currency manipulation game and pumping money into their system in order to compete with USA," Trump said on Twitter. "We should MATCH, or continue being the dummies who sit back and politely watch as other countries continue to play their games - as they have for many years!"

The U.S. Dollar Index, a basket of the greenback vs. major currencies, slid into the red following the Trump tweet before recovering.

Tweet

"He's amplifying a move that to me is happening anyway, for the right reasons," said Mark McCormick, FX strategist at TD Securities.

"It's pretty clear the currency is definitely a focus … you have some new Fed nominees which lean on the dovish side, you have the Fed ready to cut rates, you have a slowing U.S. economy," McCormick added. "There's a period here where the currency is going to weaken on these things."