President Nicolas Maduro has vowed to tighten security in cities across Venezuela after protests against his government turned deadly, killing three people and injuring 26.
"There will be no coup d'etat in Venezuela; you can rest assured. Democracy will continue, and the revolution will continue," Maduro said.
"I have given clear instructions to state security agencies to secure the main cities. Anyone who goes out to try to carry out violence will be arrested."
At least 30 people were arrested as rival protests linked to his country's deepening economic crisis exploded into violence.
A pro-government demonstrator and two student protesters were killed as rallies both for and against Venezuela's government escalated.
Unidentified assailants earlier fired into a rally outside the attorney general's office in Caracas.
National Assembly Speaker Diosdado Cabello denounced "the killing of a fighting member of the Bolivarian Revolution in the Plaza La Candelaria" 200 metres from where the opposition supporters were rallying.
"This is a provocation from the right," Cabello charged, calling for "calm and sanity".
Journalists union chief Marco Ruiz said that a photographer and a reporter were arrested while covering the protests, and that they were taken to different military detention facilities.
And Colombian news channel NTN24, which had been covering the protests in depth, was abruptly pulled off the air.
Thousands of students, accompanied by several opposition politicians, had converged in downtown Caracas to denounce the economic policies of Maduro, who succeeded the late Hugo Chavez as president last year.
"We came out for a peaceful protest and they have killed two students on us? How can this be?" asked Catholic University student Vanessa Eisi.
A day earlier, five youths were shot when more motorcycle-riding gunmen opened fire on protests in the Andean city of Merida. Ten protesters were arrested.
"We students are sick and tired of living in fear because of violent crime. We are sick of having to leave the country because when we graduate, there is nothing here," said Biaggo Alvarado.
Elsewhere in Caracas and in other cities, protesters clad in red - the colour of "Chavismo" - gathered in support of Maduro.