Europe should impose punitive tariffs on imports from the United States if President Donald Trump acts to shield U.S. industries from foreign competitors, a senior ally of German Chancellor Angela Merkel said in a newspaper interview.

Trump has already formally withdrawn the United States from the Trans-Pacific Partnership trade deal, distancing America from its Asian allies, and vowed to renegotiate the U.S. free-trade deal with Canada and Mexico.

The tycoon-turned-president has also threatened German carmakers with a border tax of 35 percent on vehicles imported into the U.S. market, saying such a levy would help create more jobs on American soil.

"If Donald Trump imposes punitive tariffs on German and European products, then Europe should also impose punitive tariffs on U.S. products," Volker Kauder, parliamentary floor leader of Merkel's conservatives, told the Funke media group in an interview published on Saturday.