Mexico is willing to talk with the US in order to maintain good relations, but paying for US President Donald Trump's border wall "is not negotiable", Mexican Foreign Minister Luis Videgaray said on Thursday.
Peña Nieto on Wednesday said he "regrets and disapproves" of Trump's proposed wall, reiterating that Mexico will not pay for it - a declaration he's made for months.
Donald Trump has threatened to cancel his upcoming meeting with Mexico's president over the country's refusal to pay for his border wall.
The Mexican president, who had been under intense pressure stand up to Trump, agreed, and said on Twitter, "This morning we have informed the White House that I will not attend the meeting scheduled for next Tuesday with the POTUS".
Ryan said that this tax, known as a border adjustment tax, would allow the U.S.to "get revenues in from Mexico to pay for something, such as a wall".
In a speech on Monday, Pena Nieto had said his government is prepared to negotiate with the U.S. if Mexico's national sovereignty is respected.
White House spokesman Sean Spicer said in the afternoon Trump favoured a plan to impose an import duty of 20% on Mexican imports to fund the wall.
Trump has also vowed to renegotiate NAFTA, the free trade agreement between the U.S., Canada and Mexico.
He had been due to meet Mexican president Enrique Pena Nieto on January 31.
The president's executive orders also call for hiring 5,000 additional border patrol agents and 10,000 more immigration officers, though the increases are subject to the approval of congressional funding.
Trump also tweeted that the USA has a Dollars 60 billion trade deficit with Mexico.
Some "60 percent of illegal migrants enter the United States with a visa", and then overstay their welcome, he said. But Trump has insisted that Mexico will pay the cost, either directly or indirectly.
Ryan also repeated a sentiment of Trump's and said that this tax on exports would mean "there is no reason to leave this country as a manufacturer, no reason to outsource".
Experts have voiced doubts about whether a wall would actually stem illegal immigration, or if it is worth the billions it is expected to cost.
"Not all Brazilians in the United States are authorized to be there", said Santoro, adding there is a "real possibility" that a crackdown will "spark a massive wave of deportations".
It is unclear what retaliatory steps Mexico could take if the border tax is approved, because exports to the USA are essential to the Mexican economy.