The latest threat came the same day that European Union placed tariffs on USA products ranging from orange juice to vodka, retaliation for Trump tariffs earlier this year on aluminum and steel.
"Anything that comes on Twitter is just really noise, I don't think you can use that as an official medium to make global policies", said Alastair Sandler, an equity sales trader at Northern Trust.
Tariffs on more than $3 billion worth of American exports to Europe took effect on Friday.
European officials have responded to Trump with tariff threats of their own on US products, including automotive products, raising prices for consumers worldwide.
This list was already sent by the European Union to the World Trade Organization (WTO) on May 18, in anticipation of Washington's decision to go through with the tariffs.
In an escalating trade war, its duties target goods worth $3.3bn (£2.5bn) after the United States imposed tariffs on the bloc's steel and aluminum.
That list includes roughly 160 products such as United States sunbeds, paper towels, corduroy trousers and porcelain tableware.
Less than a month before an expected meeting with European leaders, President Trump threatened Friday to slap 20% tariffs on Europe's cars in the latest salvo of the trade wars with USA allies. "Build them here!" he declared.
The European Union's decision to impose tariffs on some US goods is measured and proportionate, Prime Minister Theresa May's spokeswoman said on Friday, adding that tariffs would be discussed with President Donald Trump when he visits in July.
Last month, Trump instructed his Commerce Department to begin a national security investigation that would provide the legal underpinning for new tariffs on cars.
The United States has imposed tariffs on Canada, Mexico and £25bn in Chinese goods. All five countries have already announced retaliatory measures.
The list also covers bourbon whiskey - the European Union imported some 415 million euros worth from the USA in 2017, along with another 150 million euros worth of whiskey without the "bourbon" designation.
Turkey said Thursday that it's imposing tariffs worth $267 million on U.S. goods, targeting items such as coal, paper, walnuts, tobacco, rice, whiskey and cars.