MEXICO CITY — Jared Kushner, President Trump’s son-in-law and senior adviser, met with Mexico’s president on Wednesday, arriving just weeks after a planned meeting between the nations’ leaders fell apart because of a bitter phone dispute over Mr. Trump’s proposed border wall.

Mr. Kushner’s meeting with President Enrique Peña Nieto was meant to soothe tensions. Plans for the two presidents to meet have been abruptly canceled at least twice since Mr. Trump took office, and the relationship between their countries is suffering its roughest patch in decades.

But the encounter between Mexico’s president and Mr. Kushner, a political newcomer whose top-secret security clearance was stripped last month, underscored the profound shift in approach that the Trump administration has taken with Mexico, and with the region more broadly.

Officials announced the visit less than a day before it happened, offering no guidance on what would be discussed.