MEXICO CITY, May 30 (Xinhua) -- Mexican President Andres Manuel Lopez Obrador on Thursday proposed deepening dialogue with the United States to solve the migrant issue on the U.S.-Mexico border.

In a letter to his U.S. counterpart Donald Trump, Lopez Obrador said that social problems "are not resolved with taxes or coercive measures."

Lopez Obrador sent the letter after Trump said on Twitter on Thursday that the United States will impose a new 5-percent tariff on all imported Mexican goods beginning June 10 so as to pressure the country to halt undocumented migrants crossing the border.

In a statement released on Thursday evening, the White House said if the situation on the U.S.-Mexico border is not improved, the tariff will be raised to 10 percent on July 1, 2019.

Trump has repeatedly threatened Mexico with tariffs over the issue. The U.S. Customs and Border Protection turned away or apprehended more than 103,000 migrants at the U.S.-Mexico border in March, the highest in the past six years.