Europe will implement counter-measures against U.S. tariffs on steel and aluminium, German Chancellor Angela Merkel said on Sunday, voicing regret about President Donald Trump's abrupt decision to withdraw support for a Group of Seven communique.

"The withdrawal, so to speak, via tweet is of course ... sobering and a bit depressing," Merkel said in an ARD television interview following the G7 summit in Canada.

Just like Canada, the European Union is preparing counter-measures against U.S. tariffs on steel and aluminium imports, Merkel said.