One U.S. libertarian group has hit out at the Trump administration's new import tariffs on steel and aluminum, saying "it's very hard to understand what has gotten into the President."

That's especially so when industries that use steel collectively contribute more to U.S. growth and employ more workers as compared to the steel producers, said Daniel Ikenson, director of the Cato Institute's trade policy studies center.

"The economics don't make a whole lot of sense, we're going to hurt ourselves," Ikenson told CNBC Friday.

"It's very hard to understand what has gotten into the President, maybe he is not rational but this is really going to cause great upheaval and it's going to weaken the global trading system," he added.

President Donald Trump announced the new tariffs on Thursday, which has since drawn criticism from many parties, including steel exporters around the world, U.S. businesses and both conservative and liberal leaning groups.

"All along I have assumed that the President is rational and that he would recognize the economic costs and the political costs. All these information have been put before him time and again by many of his advisers, and he seems just so intent on imposing duties that he's neglecting to really take into consideration these costs," Ikenson said.

Ikenson said it is estimated that economic contribution by the steel-using industries is 15 times more than the steel producers. In addition, such businesses employ 57 workers to every one employee of the steel producers, he said.

Major steel and aluminum users in the U.S. include the automobile sector, construction, aerospace and even the beverage industry.