President Donald Trump just made a case for "worldwide trickle down" economics during his speech at the World Economic Forum, CNBC's Jim Cramer said Friday.

"Davos is a conversation about how to get the poor to be rich," Cramer said on "Squawk on the Street," shortly after the president's "America First" speech in Davos, Switzerland.

Trump spoke "about how to get the rich to be even richer and therefore the poor will do better. Kind of a worldwide trickle down," Cramer contended.

Trickle down theory, popularized during the presidency of Ronald Reagan, maintains that cutting taxes, particularly for U.S. companies, will spur economic growth and help everyday Americans. There's been a fierce debate years, split largely along party lines, on whether it works.

Trump, the first sitting U.S. president in 18 years to address the annual conclave of the rich and powerful, said the U.S. was "open for business," casting the U.S. as a hospitable business environment, boosted in part by the corporate tax cut enacted by Republicans last year.