Mexican Foreign Affairs Secretary Marcelo Ebrard, right, accompanied by Mexican Ambassador to the U.S. Martha Barcena, speaks during a news conference at the Mexican Embassy in Washington, June 3, 2019.
Mexican Foreign Affairs Secretary Marcelo Ebrard, right, accompanied by Mexican Ambassador to the U.S. Martha Barcena, speaks during a news conference at the Mexican Embassy in Washington, June 3, 2019.

Mexico warned Monday that President Donald Trump's threatened new tariff on its exports to the United States would hurt both countries' economies and cause even more Central American migrants to travel through Mexico to reach the United States.

At the start of talks in Washington, Mexican officials said they could only go so far in meeting Trump's demand to block migrants' passage through Mexico to avert Trump's imposition of a 5% tariff next week. The officials specifically ruled out a "third safe country" agreement requiring U.S. asylum-seekers to first apply for refuge in Mexico.

FILE - Mexico's Economy Minister Graciela Marquez looks on during a news conference after attending a meeting in Mexico City, Mexico, May 10, 2019.
US, Mexican Officials to Meet on Immigration and Tariff Threat

As U.S. and Mexican teams launch talks this week in Washington, U.S. President Donald Trump says he is "really okay" proceeding with his threat to impose tariffs on Mexican goods unless Mexico does more to cut the number of Central American migrants reaching the border.

"Everyone is coming through Mexico -- including drugs, including human trafficking -- and we're going to stop it or we're not going to do business and that's going to be it. It's very simple," Trump told reporters late Sunday."We'll see what can be done.

"There is a clear limit to what we can negotiate, and the limit is Mexican dignity," Mexico's ambassador to the United States, Martha Barcena, said.

Barcena added that U.S. tariffs "could cause financial and economic instability," reducing Mexico's capacity to address the flow of migrants and "offer alternatives" to people fleeing Guatemala, Honduras and El Salvador.

Mexican officials contended that an additional quarter million migrants could try to reach the U.S. if the tariff is imposed, on top of the tens of thousands already reaching the southern U.S. border each month.

U.S. Border Patrol agents keep watch on a large group of migrants who they say were attempting to cross the U.S.-Mexico border illegally, in El Paso, Texas, May 29, 2019.

Before leaving for a state visit in Britain, Trump, who earlier this year threatened to close the U.S.-Mexico border, on Sunday goaded Mexico for a quick resolution to the latest snag between the neighboring countries.

U.S. lawmakers returning to Washington after a weeklong congressional recess sharply criticized Trump's latest tariff tactic aimed at a major U.S. trading partner.

FILE - Senate Majority Whip Sen. John Cornyn, R-Texas, Chair of the Senate Judiciary Border Security and Immigration Subcommittee, speaks during a hearing about the border, May 8, 2019, on Capitol Hill in Washington.

"This [tariffs] is not a popular concept," Republican Sen. John Cornyn said of public opinion in Texas, which he represents. "Mexico is our biggest export market."

Another Republican, Missouri Sen. Roy Blunt, expressed concerns that trade friction could harm a newly negotiated free trade pact between the United States, Mexico and Canada.

"I'm not a big advocate of tariffs, and I'd like to get the USMCA agreement approved," Blunt told VOA. "I don't see how the addition of a tariff [on Mexican goods] right now helps make that happen."

"Mexico is a critical trading partner of the United States," Democratic Sen. Ben Cardin of Maryland said. "You put up barriers, it's going to end up costing us jobs, and it's going to cost consumers."

Cardin added that Trump's threatened tariff "would be counterproductive," as far as boosting U.S. border security.

"If we need cooperation on the southern border, they (Mexican officials) are not going to give us cooperation. Why bother if we're going to have an antagonistic relationship?" Cardin said.

Trump is signaling no second thoughts. As he left for London, he said he is "really okay" with the new tariff, unless Mexico does more to cut the flow of migrants reaching the U.S. border.

"Everyone is coming through Mexico — including drugs, including human trafficking — and we're going to stop it or we're not going to do business, and that's going to be it. It's very simple," Trump told reporters.

Mexican President Andres Manuel Lopez Obrador, meanwhile, called for dialogue to resolve tensions rather than "coercive measures."

Lopez Obrador said his government is a friend of the U.S. government, that he wants to remain a friend of Trump, and that the Mexican people are friends with the people of the United States.

"Let us swear that nothing and nobody separates our beautiful and sacred friendship," Lopez Obrador wrote on Twitter.

Michael Bowman contributed.