Ali Rodriguez in 2012. (Fernando Vergara/AP)

Alí Rodríguez, a major figure in Venezuela’s socialist revolution who went on to serve in top government posts, died Nov. 19 in Havana, where he had served as ambassador to Cuba since 2014. He was 81.

Venezuela’s state television network reported his death. The cause was not disclosed.

At different times, Mr. Rodríguez oversaw the mass firing of thousands of workers at Venezuela’s state-run oil company PDVSA. He also defended the sharply anti-American foreign policy of the socialist governments of the late President Hugo Chávez and current President Nicolás Maduro.

“His experience and honesty were a school for all of us,” Maduro said on Twitter. He called Mr. Rodríguez “a tireless fighter” who was “indispensable to the revolution.”

Alí Rodríguez Araque was born in Venezuela’s central state of Lara on Sept. 9, 1937. He joined guerrilla fighters as a young man inspired by the Fidel Castro-led revolution in Cuba and became known as an expert in explosives. His nickname was “Comandante Fausto.”

The revolutionary fervor in Venezuela, however, never captured mass appeal, and in the 1970s most rebel groups surrendered.

After former Venezuelan President Rafael Caldera reached a peace pact with the rebels, Mr. Rodríguez and others were granted amnesty for crimes that included kidnappings, bomb attacks and bank robberies.

In the 1980s, Mr. Rodríguez joined the Causa R party. He eventually became a central figure in Fatherland for All — another political party that supported then-presidential candidate Chávez.

Later elected to Venezuela’s National Assembly, Mr. Rod­rí­guez made a reputation for himself as a negotiator and consensus-seeker, although he was always a staunch opponent of opening up the oil sector to private investment in the 1990s.

A lawyer who did postgraduate studies in economics, Mr. Rod­ríguez was an influence on Chávez and was appointed minister of energy and mines at the beginning of Chávez’s first term in 1999. A year later, he left the position to serve as secretary general of OPEC.

In 2002, Mr. Rodríguez was appointed president of PDVSA, where he failed to resolve an internal conflict that led to a widespread walkout. To break the strike, 18,000 employees were fired — nearly half of the oil firm’s payroll.

In the years that followed, ­PDVSA recovered and became the world’s fifth-largest oil producer, turning out more than 3 million barrels per day. But financial losses after the strike were steep, and the company never regained its engineering talent. Production is now at its lowest point in decades.

Mr. Rodríguez served as president of PDVSA until November 2004.

Information about survivors was not available.