The leaders also will direct their teams to create a task force to fight criminal organizations and curb the flow of fentanyl, the statement said, as well as working groups focused on issues such as labor and worker protections.

The Mexican president also met with Vice President Kamala Harris, who has the responsibility of addressing the economic and social strains that the U.S. administration has said is a driving force behind border crossings. She met last year with Mr. López Obrador in Mexico. The two on Tuesday talked about the need for public-private partnerships for investments in the region, the White House said.

Recent moves by Mr. López Obrador have challenged U.S. goals in the region. But Mr. Biden pushed back on any suggestions of friction between the two leaders. “Despite the overhyped headlines that we sometimes see, you and I have a strong, productive relationship,” he said as he opened the meeting in the Oval Office.

In June, Mr. López Obrador boycotted Mr. Biden’s regional Summit of the Americas in Los Angeles, which encouraged other Latin American leaders to stay away after the U.S. excluded Cuba, Nicaragua and Venezuela from the meeting. At the summit, the U.S. signed a migration agreement with several Latin American countries, including Mexico, that committed more countries to receiving migrants and providing more pathways for them to live legally.

In April, the U.S. had made more than a million arrests at the U.S.-Mexico border in six months, the fastest pace of illegal border crossings in at least the last two decades, according to data from U.S. Customs and Border Protection.

On July 4, Mr. López Obrador said the U.S. should dismantle the Statue of Liberty if the Biden administration doesn’t drop spying charges against Mr. Assange, who recently appealed his extradition from the U.K. He has said Mexico would grant Mr. Assange asylum if he is freed.

White House press secretary

Karine Jean-Pierre

declined to respond directly to the Mexican president’s comments. “There will be many conversations that will be had,” she said. “And I’m going to leave it at that.”

Senior administration officials later said the charges against Mr. Assange weren’t an issue Mr. Biden would focus on. Mr. López Obrador didn’t bring up Mr. Assange in his public remarks at the start of the meeting.

Shannon O’Neil,

a fellow at the Council on Foreign Relations in New York, said such comments from Mr. López Obrador amounted to a missed opportunity for Mexico. “Instead of defining and laying out Mexico’s broad concerns and asks of its neighbor, López Obrador is focused on taunts and provocations,” she said.

The visit to Washington, Mr. López Obrador’s second since Mr. Biden took office, comes after 53 migrants, more than half of them Mexicans, died when they were left in a truck in San Antonio, in one of the deadliest migrant tragedies on U.S. soil.

Mr. López Obrador pushed Mr. Biden to increase the number of U.S. visas for guest workers from Mexico and Central America to deter illegal migration, telling him he should ignore criticism from his GOP opponents. “I know your adversaries, the conservatives, are going to be screaming all over the place,” he said. “The way out is not through conservatism. The way out is through transformation. We have to be bold in our actions.”

The senior Biden administration officials said the two countries didn’t plan to announce additional work visas, adding that the closed-door meeting would be more focused on the implementation of existing visa commitments.

Mr. López Obrador’s rhetoric ahead of Tuesday’s meeting contrasts with the cautious tone he used with former President

Donald Trump,

who threatened to impose tariffs on Mexican exports if Mexico didn’t take stronger measures to curb rising migration from Central America. In response, Mr. López Obrador deployed thousands of soldiers and immigration agents to stem the flow of migrants.

In 2020, Mr. López Obrador sent a letter to Mr. Trump asking him to pardon Mr. Assange. The letter wasn’t answered. Mr. López Obrador said he would bring up the subject of Mr. Assange with Mr. Biden. Mr. López Obrador has a fraught relationship with local media critical of his government, but he defends Mr. Assange, whom he calls courageous and “the world’s best journalist of our time” who has been unfairly treated. At the July 4 conference, he said that if Mr. Assange received the maximum sentence, which implies he would die in prison, “we have to start the campaign to dismantle the Statue of Liberty…because it’s no longer a symbol of liberty.”

His comments are unlikely to jeopardize bilateral ties or the relationship between the two heads of state, primarily because of Mexico’s leverage over immigration policy, former diplomats say.

“President Biden needs Mexico’s cooperation,” said

John Feeley,

a former U.S. ambassador to Panama who also held senior diplomatic posts in Mexico. Mr. Feeley said he hoped that Mr. Biden would deliver a “strong private message” to Mr. López Obrador raising U.S. concerns.

Thousands of Mexican soldiers and immigration agents break up caravans of migrants and help turn away hundreds of thousands of asylum seekers heading to the U.S. as apprehensions at the U.S. southern border approach a record-high two million this fiscal year.

“Biden is pragmatic. A public rift would not favor Biden and benefit López Obrador domestically,” said

Martha Bárcena,

who served as Mexico’s ambassador to the U.S. from 2018 to 2021. But Mexico is treading a thin red line. “If the U.S. perceives Mexico crossed it, there could be problems,” she added.

Mr. Biden said his government was “also accelerating our efforts to stop the illegal trafficking of fentanyl” and working to slow human smuggling.

Criminal organizations such as Mexico’s Sinaloa and Jalisco cartels are the leading suppliers of fentanyl to the U.S. Last week, Mexican soldiers seized more than half a ton of fentanyl in Sinaloa, a record haul.

Mr. López Obrador’s energy agenda—in which he seeks to strengthen the dominant role of Mexico’s state oil company and the public power utility at the expense of private and foreign investors—has led to clashes with U.S. energy companies.

U.S. Trade Representative

Katherine Tai

has expressed concerns about Mexico’s compliance with provisions of USMCA—the trade deal with Mexico and Canada—regarding its energy policies.

In the joint statement, the leaders pledged their countries would seek “full implementation” of the trade deal and become “global leaders in clean energies and actions to combat climate change.”

Mr. López Obrador said Tuesday that the trade deal left “margins for us to intensify our bilateral relationship.” A longtime admirer of Franklin D. Roosevelt, Mr. López Obrador urged Mr. Biden to revive Mr. Roosevelt’s “good neighbor” policy between the U.S. and Mexico.

A senior Mexican official said trade and investment disagreements over energy policies won’t strain bilateral ties. “Fortunately, we have a predetermined route to solve any difference under the trade deal,” the official said.

—José de Córdoba contributed to this article.

Write to Juan Montes at juan.montes@wsj.com and Tarini Parti at Tarini.Parti@wsj.com