"There has been some misreporting today about side agreements and things like that," Mnuchin said on "Lou Dobbs Tonight." "There's no side agreements. The only way the president will be reducing the tariffs is if there is a phase two part of the agreement that is also fully enforceable."
Mnuchin called this "giant step" on phase one of the trade deal "an enforceable agreement."
"This is a great win for American business and American farmers."
"The president has been very clear since his first meeting with President Xi there were two issues here," Mnuchin said. "One was he wanted to reduce the trade deficit, and two -- he wanted structural changes particularly around technology and other issues."
Beijing agreed to purchase $200 billion worth of U.S. goods over the next two years, and Trump has touted the prospect of China buying $40 billion to $50 billion of American agricultural products.
Mnuchin called the additional $200 billion "very significant."
"This is a great win for American business and American farmers," Mnuchin said.
Mnuchin praised Trump for being the first president to negotiate such a historic trade deal. In addition to it being a significant trade deal for America, Mnuchin said he believes it can be a good deal for China, too.
"They've got a large, growing middle-class, and if our companies can compete fairly, selling things to that middle class, that's a huge, growing market for our workers," Mnuchin said.
Mnuchin's comments coincide with U.S. Trade Representative Robert Lighthizer's comments to Dobbs on Monday when he explained how select tariffs will work.
"We maintain $380 billion worth of tariffs on important products," Lighthizer said. "So across the board is a really, really good deal for the United States. And it will work if reformers in China want it to work. And if that happens, great. If it doesn't happen, it's fully enforceable."
"Ambassador Lighthizer really did a phenomenal job," Mnuchin said. "We had people in every single agency dedicated under his work, getting this done."
Mnuchin said Lighthizer will be leading the enforcement office, and if there are any disputes, it will come to his office.
The president has previously suggested that a complete trade deal could involve two or three phrases.
"At a later date I will be going to Beijing where talks will begin on Phase Two!" Trump wrote on Twitter when announcing the "phase one" signing.
Although Trump previously suggested the second phase could come immediately after the first, he does not have any imminent plans to visit China for further trade talks, sources told FOX Business.
The U.S. also agreed to no longer label China as a currency manipulator in conjunction with "phase one."
The Treasury Department designated China as a currency manipulator on Aug. 5, after the yuan fell to a more than 10-year low against the U.S. dollar. At the time, Treasury pointed to Beijing’s “long history of facilitating an undervalued currency through protracted, large-scale intervention in the foreign exchange market” as the reason for the designation.
With the text of the trade deal still not made public and without an opportunity to vote yay or nay, Senate Minority Leader Chuck Schumer said Monday that he is disappointed in the reported deal. He asked Trump to answer six questions about the agreement before the Wednesday signing.
"China pledging to make short-term purchases of American goods will not address the fundamental problems that undermine long-term U.S. economic opportunity, prosperity, and security," Schumer wrote in a letter.
Democrats unhappy with Trump's progress on the trade deal this fall seemed irked by the administration's ability to fly solo.
"Donald Trump should know that any meaningful trade deal is only legitimate because of the authority granted to him by Congress, and that authority can be taken away," Sen. Ron Wyden, D-Ore., told Bloomberg in October.
FOX Business' Evie Fordham, Audrey Conklin, Jonathan Garber, Edward Lawrence and R.N. White contributed to this report.