WASHINGTON — President Trump signed an executive order on Thursday that will push for federal dollars spent on infrastructure projects to be put toward American companies and bolster workers his top trade adviser described as “blue-collar Trump people” the administration has focused on helping.

That description, given to reporters by Peter Navarro, the White House trade adviser, was a small but telling glimpse at how the administration has sought to carry out the president’s “America First” policy. The executive order is meant to be an economic shot in the arm for workers held up as symbols of the president’s tough-on-trade stance, even as some have faced shaky economic prospects over the administration’s decisions to impose high tariffs on imported goods and to start several global disputes, including a damaging trade war with China.

Flanked by officials including Mr. Navarro and Labor Secretary Alexander Acosta in his first public appearance since the government reopened on Friday, Mr. Trump said during a 40-minute session with reporters that the reasoning behind the order was that “we don’t get treated great by many countries in terms of our trade deals.” The president added that he wanted infrastructure projects to be built with “American steel,” “American iron” and “American hands.”

The executive order, “Strengthening Buy-American Preferences for Infrastructure Projects,” will recommend but not outright require that what the administration said was $700 billion in federal financial assistance doled out by some 30 agencies each year go toward American-manufactured products, including aluminum, steel, concrete and iron. The order will also seek to tamp down on waivers that agencies have used to bypass American products in favor of foreign-made ones.