Mexico will not pay for Donald Trump's border wall, the country's president has said in a message to the nation.
Enrique Pena Nieto said he "lamented" the plans for the barrier, adding that "Mexico doesn't believe in walls".
But he made no mention of cancelling or postponing a trip to Washington on 31 January to meet the new US president.
Mr Trump has signed an executive order for an "impassable physical barrier" and has insisted Mexico would reimburse the US for it.
Mr Pena Nieto said: "I've said time and again; Mexico won't pay for any wall.
"It comes as our country is talking on new rules on cooperation, trade, investment, security and migration in the North American region.
"As president I assume the complete responsibility to defend the interests of Mexico and Mexicans.
"Based on a final report by the functionaries in Washington DC and advice from the chamber of commerce, governors, and so on, I will decide the right next steps to take.
"Mexico offers its friendship to the American people and its willingness to reach accords with their government. Agreements that will be in favour of both Mexico and the US."
Billions of dollars
Mr Trump said in a TV interview with ABC News that Mexico would "absolutely, 100%" reimburse the US for his wall.
But Congress would have to approve funding for the structure, which is estimated to cost billions of dollars.
Building a 2,000-mile barrier along the Mexican border was one of Mr Trump's key pledges in the presidential election campaign.
He spoke of a "crisis" on the southern US border as he signed the directives during a ceremony at the Department of Homeland Security on Wednesday.
The orders also called for hiring 10,000 immigration officials to help boost border patrol efforts.
"A nation without borders is not a nation," he said. "Beginning today the United States gets back control of its borders."
The executive orders are among a flurry expected on national and border security this week.
Mr Trump is next expected to announce immigration restrictions from seven countries with Muslim-majority populations in the Middle East and Africa. This could affect refugee programmes.
These countries are believed to be Syria, Iraq, Iran, Libya, Sudan, Somalia and Yemen.