Trump suggested in his tweet that the USA would not impose the aluminum and steel tariffs on the European Union if they dropped their tariffs. He also added Australia to the list of likely carve-outs.
The list is being finalized but so far includes US steel and agricultural products, as well as other products such as bourbon, peanut butter, cranberries and orange juice.
She said, "trade creates wealth, when it is based on exchange and cooperation" and added, referring indirectly to the surprise resignation of Trump's top economic adviser Gary Cohn Tuesday, that, "advocates for this in the USA administration are very important".
Trump insisted in a phone call with French President Emmanuel Macron - a leading European Union player staunchly opposed to the tariffs - that the "decision is necessary and appropriate to protect national security".
Along with a huge range of steel products, the EU's hit list of flagship American products lined up for counter measures includes peanut butter, bourbon whiskey and denim jeans.
Trump announced Thursday that he was slapping tariffs of 25 percent on imported steel and 10 percent on aluminum, but he temporarily exempted big steel producers Canada and Mexico - provided they agree to renegotiate a North American trade deal to his satisfaction. The EU also hopes "to convince the USA administration that this is the right move".
European Union Trade Commissioner Cecilia Malmstrom will host her US and Japanese counterparts in Brussels on Saturday, with impending USA tariffs on metal imports set to dominate talks.
Trade tensions between Washington and Beijing have risen since Trump took office a year ago. "These are measures that would defend our interests".
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Russian Foreign Minister Sergei Lavrov dismissed Britain's warnings of retaliation were propaganda and not serious. A police officer, one of the first responders to the incident, also fell seriously ill at the scene.
The EU itself already has tariffs on many imports.
Within minutes of Trump's announcement, U.S. Republican Senator Jeff Flake, a critic of the president, said he would introduce a bill to nullify the tariffs.
China's steel and metals associations urged the government to retaliate, citing imports from the United States ranging from stainless steel to coal, agricultural products and electronics.
"President Trump has recently said and I quote, 'trade wars are good and easy to win, '" Tusk told a press conference in Luxembourg.
Some Democrats praised the move.
"We call for calm-headed behavior", he told reporters in Brussels.
The EU says that its exports should be excluded from the measures. According to Reuters, Japanese Trade Minister Hiroshige Seko will also join the meeting in Brussels.
In talks, the United States should not expect any European Union concessions to win an exemption, European Union officials said.