The president's comments came shortly after his foreign minister and chief negotiator, Marcelo Ebrard, told the rally the country had emerged from the high-stakes talks that avoided U.S. tariffs on Mexico's exports with its "dignity intact."
López Obrador said that as an admirer of Gandhi, Martin Luther King and Nelson Mandela he opposes retaliation but had been prepared to impose tariffs on U.S. goods. "As chief representative of the Mexican State I cannot permit that anyone attacks our economy or accept an unjust asymmetry unworthy of our government."
The rally in Tijuana, a short walk from the border, was originally scheduled as an act of solidarity in the face of President Donald Trump's threat to impose a 5% tariff on Mexico's exports if it did not stem the flow of Central American migrants crossing its territory toward the U.S.
But after Mexican and U.S. officials reached an accord late Friday that calls on Mexico to crackdown on migrants in exchange for Trump backing off his threat, officials here converted the rally into a celebration.
Ebrard, who helped negotiate the deal, said when he gave the president his report, he told López Obrador: "There are no tariffs, Mr. President, we emerged with our dignity intact."
Speaking about the migrants, Ebrard said, "while they are in Mexico, we are going to be in solidarity with them."
A series of speakers at the government-organized gathering spoke of the importance of the U.S.-Mexico relationship and applauded Mexico's negotiating team. The rally had the feeling of a campaign event with lots of paraphernalia from López Obrador's ruling Morena party.
Lopez Obrador spoke of the long and intertwined histories of the two countries, noting that they "are protagonists in the largest demographic exchange in the world."
Tijuana residents at the rally said they supported the terms of the agreement. But residents just a block away expressed concern the deal could mean more asylum seekers having to wait in Tijuana and other Mexican border cities for the resolution of their cases in the U.S. That process can take months or even years.
Critics of the deal in Mexico say that other than a vague reiteration of a joint commitment to promote development, security and growth in Central America, the agreement focuses almost exclusively on enforcement and says little about the root causes driving the surge in migrants seen in recent months.
The deployment of 6,000 National Guard troops appears to be the key commitment in what was described as "unprecedented steps" by Mexico to ramp up enforcement, though Interior Secretary Olga Sánchez Cordero said that had already been planned and was not a result of external pressure.
Another key element of the deal is that the United States will expand a program known as the Migrant Protection Protocol, or MPP. According to Mexican immigration authorities, since January there have been 10,393 returns by migrants to Mexico while their cases wend their way through U.S. courts.
Observers said a concern is that if the MPP rolls out on a mass scale along the United States' entire southern border, it could overwhelm Mexican border cities.