Initial 45 days to come up with a plan on border security approved by the Mexican government.
Washington Post photographer Jabin Botsford captured and tweeted a photo of the piece of paper, a portion of which can be read to say "the Government of Mexico will take all necessary steps under domestic law to bring the agreement into force with a view to ensuring that the agreement will enter into force within 45 days".
Under duress because of Trump's threat to impose tariffs unless Mexico acted to stem the surge in migrants that has overwhelmed USA detention facilities and its immigration court system, Mexico signed a pact last week agreeing to control the flow of people from Central America, including deploying 6,000 members of a new national guard along its border with Guatemala.
The controversial - and teetotal - United States president was talking to anchor Joe Kernen on the station's flagship news and markets program Squawk Box on Monday about his imposition of tariffs on China, when he raised the "unfair" issue of tariffs on wine.
"The New York Times wrote a story like I already made the deal, it's nonsense, we talked about it for months and months and they wouldn't get there and we just said, hey look if you don't get there we're just going to have to charge you hundreds of billions of dollars in taxes", Trump said.
The deal reached between the North American neighbors includes deployment of Mexican soldiers on its border with Guatemala, additional arrests of migrants, and the acceptance of additional asylum seekers returned from the USA, according to the Washington Post.
"Outside of what I have just explained, there is no agreement", Mexico's Foreign Affairs Minister Marcelo Ebrard said on Monday.
But officials in Brussels have repeatedly stressed they will not discuss agriculture, drawing the ire of the Trump administration, which wants farm access to Europe.
Ebrard said this week that Mexico's Senate would need to be consulted about any such changes.
In bright sunshine outside the White House, Trump waved what he said was the text of an agreement Mexican and USA officials signed Friday to avert the application of tariffs on their exports to the United States.
Vice President Mike Pence also referred to a regional approach, suggesting Guatemala could receive asylum seekers from its neighbors.
Trump, who famously does not drink alcohol, said he would work to open the European market, again accusing France of creating unfair trade barriers to USA wine exports.
USA producers complain that French wines get to U.S. shelves "for nothing", he said, adding that "it's not fair and we'll do something about it". He gave no more details.
Six-thousand Mexican troops are headed south to the Guatemalan border to slow migrants bound for the US.