Mexico's President Andres Manuel Lopez Obrador warned Friday he would not allow the US to conduct cross-border armed operations, after Donald Trump vowed to designate Mexican drug cartels as terrorist groups.

The US president has been talking tough on the powerful drug cartels since one was allegedly responsible for the massacre of nine women and children from a US-Mexican Mormon community in northern Mexico on November 4.

Trump tweeted after the killings that the US was ready to help Mexico "wage war on the drug cartels," and he followed up this week by vowing to add Mexican cartels to the US blacklist of Foreign Terrorist Organizations.

That insulted national pride in Mexico, which resents a long history of armed interventions by its giant northern neighbor, and where Trump's comments have been taken as a threat of armed cross-border operations.

"Armed foreigners cannot intervene in our territory. We will not allow that," Lopez Obrador said.

He was quick to add that he considered any such operations unlikely, saying there was "great cooperation" between the neighbors and that Trump had always treated him "respectfully."

"In the unlikely case that a decision is taken that we consider affects our sovereignty, then we will act within the framework of international law, but I see it as unlikely," said the leftist leader, who took office one year ago.

US Attorney General William Barr will visit Mexico City next week for talks, said Mexican Foreign Minister Marcelo Ebrard.

Lopez Obrador, for his part, is due to meet Monday with family members of the slain Mormons.

Mexico deployed its army to fight drug trafficking in 2006, but experts blame the so-called "drug wars" for a spiral of violence, as fragmented cartels fight each other and the military.

The country has registered more than 250,000 murders since deploying the army into the streets, including an all-time high of 33,743 last year - a record that looks set to be broken again this year. Trump made his controversial comments in a radio interview with conservative media personality Bill O'Reilly.