GENEVA (Reuters) - Fiat Chrysler boss Sergio Marchionne called for a cooling-off over U.S. threats to impose tariffs on steel, aluminium and European car imports, warning the resulting "noise" was complicating talks on the future of the North American Free Trade Area (NAFTA).

"We need to be careful and we need to keep our cool. We need to wait until the noise stops," Marchionne told reporters at the Geneva auto show after U.S. President Donald Trump threatened new tariffs on European cars in response to criticism of his plans to tax metal imports.

"People are shooting whatever they can get their hands on across the bows," Marchionne said. "I find that very unhelpful."

He added: "If people have not yet recognised that the Trump administration is attempting to correct what it sees as a number of injustices ... (they) are going to run into trouble."

The tit-for-tat threats are "having severe repercussions on the alleged progress that was being made on the NAFTA negotiations," the FCA chief executive said.

"It does condition the investment profile of FCA as we look to both Mexico and Canada as investment locations," he said.

Revocation of NAFTA "would make all those decisions suspect", Marchionne said, but added: "I won't be throwing knives now - it's the wrong answer and the wrong time."

(Reporting by Laurence Frost and Edward Taylor; Editing by Mark Potter)