Mexican President Andres Manuel Lopez Obrador said Thursday that he would write to US President Joe Biden to insist on the need to tackle the causes of migration from Central America.
"I will send him a letter because we cannot just be detaining" migrants, Lopez Obrador said at his daily news conference.
"We must address the causes. People do not leave their towns for the pleasure," he said.
Lopez Obrador has repeatedly proposed expanding one of his domestic welfare programs into Central America in the aim of generating 1.2 million jobs in the region.
The scheme, named Sembrando Vida, provides economic grants to agricultural producers.
Lopez Obrador has also proposed allowing participants to qualify for a US work visa after three years.
Authorities in southern Mexico this week detained dozens of mostly Central American migrants, including children, heading for the United States on foot as they seek to escape poverty, violence and other problems.
"The purpose is to keep migrants in the southeast of the country as far as possible," Lopez Obrador said.
Allowing them to travel across Mexico "brings many risks of human rights violations, especially on the northern border," he said.
Mexico has seen increased arrivals of undocumented migrants heading north following Biden's arrival in the White House with a promise of a more humane approach.
US Vice President Kamala Harris also stressed the need to tackle the root causes of migration when she visited Mexico in June, but cautioned that it would take time.