US President Donald Trump appeared to strike a change in tone late on Wednesday after a friendly phone call with Colombian President Gustavo Petro, one of the US president's fiercest critics. 

"It was a great honor to speak with the president of Colombia, Gustavo Petro, who called to explain the situation of drugs and other disagreements that we have had," Trump wrote on his social media site.

"I appreciated his call and tone, and look forward to meeting him in the near future," Trump said, while inviting Petro to the White House. 

Trump's testy ties with Petro

The surprise change of tone came days after Trump called Petro a "sick man who likes making cocaine and selling it to the United States," in the wake of the US operation that ousted Venezuelan leader Nicolas Maduro.

When asked by a reporter last weekend whether the US would carry out a similar operation on Colombia, Trump said, "It sounds good to me."

Trump has also warned other Latin American countries including Cuba and Mexico in the wake of the Venezuelan operation.

Petro, a leftist leader, has frequently clashed with Trump ever since the US president returned to office last year. Petro denounced the weekend raid in Caracas, calling it an "abhorrent" violation of Latin American sovereignty.

Amid an ongoing spat, the Trump administration has leveled sanctions against Petro and other members of his family, accusing him of failing to curb the flow of cocaine into the US.

Colombia has long been America's staunchest ally in Latin America, and at the center of the US counternarcotics strategy abroad.

Petro confirms talks with Trump

Petro told protesters late Wednesday — whom he'd asked to mobilize against US military threats — that he had spoken with Trump.

"We have spoken by phone for the first time since he became president," Petro told supporters gathered at a rally in the capital, Bogota.

"I talked about two things: Venezuela and the issue of drug trafficking," he said, adding he had requested a restart of dialogue between the two countries.

The phone call was "cordial" and "respectful," a source in Petro's office told Reuters.

Edited by: Zac Crellin