U.S. Treasury Secretary Steven Mnuchin said the new North American trade agreement will give the U.S economy a boost.

"I think we are going to get an excess 50 basis points of additional growth in GDP as a result of this agreement. People who say this is just the NAFTA 2.0 just don't understand the technicalities of this agreement," Mnuchin said on CNBC's "Squawk on the Street" on Thursday.

"This is a whole new agreement that really brings the trading relationships into the modern era," Mnuchin added. "This is our largest trading block — incredibly important to U.S. workers and U.S. farmers. This addresses everything from enabling small businesses to be able to compete more fairly, to expanding agricultural opportunities in opening markets, to protecting digital trade."

House Democrats and the Trump administration had worked for more than a year to resolve Democratic concerns about enforcement tools for labor and environmental standards under the new deal, known as the United States-Mexico-Canada Agreement. Both sides agreed to move forward with the accord last week.

"This is a very, very detailed agreement ... Ambassador Lighthizer has led an interagency team that has impacted almost every single one of our agencies," Mnuchin said.

Economic activity in the U.S. grew at an annualized rate of 1.9% in the third quarter, down slightly from the 2% pace in the second quarter.

The deal made a few key changes from the North American Free Trade Agreement, which took effect in 1994. U.S. farmers got better access to the Canadian dairy market, rules of origin for auto parts became more strict, nearly half of automobile parts had to be produced by workers who make at least $16 an hour, and digital trade and intellectual property rules were updated, among other provisions.

— CNBC's Jacob Pramuk contributed to this report.