The unnamed source made the announcement on Wednesday, regarding the talks that began last year, AFP reported.
The third round, initially slated to be held in December 2014, have been called off twice.
"Now there is a new date for a round of negotiations on March 4 and 5," an EU diplomat said. "The EU condition is that Cuba does not ask for restrictions on the subjects discussed, particularly on human rights issues and the role of civil society."
The third round was reportedly aimed at dealing with issues related to human rights.
This round, to be held in the Cuban capital, is supposed to pave the way for the normalization of ties between Havana and the EU.
After more than 50 years, Cuba and the United States renewed relations following an accord on December 17, 2014 that marked a "historical turning point," as put by EU foreign policy chief Federica Mogherini.
The EU was also seeking to "expand relations with all parts of Cuban society," she noted at the time.
Washington placed an official embargo against Cuba in 1962. They became ideological foes soon after the 1959 revolution that brought Fidel Castro to power.