But Venezuelan authorities said they had suppressed a military rebellion near the central city of Valencia.
The ruling Socialist Party’s deputy, Diosdado Cabello, said there had been a “terrorist attack” at a military base in Valencia and a witness reported hearing gunshots overnight.
Mr Cabello said several arrests have been made.
Opposition protesters clash with security forces in Venezuela
Troops acted quickly to control the situation at the Paramacay base in the central city of Venezuela, Mr Cabello said on Twitter.
A witness in Valencia, roughly two hours from the capital of Caracas, told Reuters she heard shooting overnight.
The announcement came after a small group of men dressed in military fatigues, some armed with assault rifles, released a video declaring themselves in rebellion in Carabobo state, where Valencia is located.
In the video a man identifying himself as Captain Juan Caguaripano said any unit refusing to go along with its call for rebellion would be declared a military target.
“We demand the immediate formation of a transition government,” he said. He was flanked by about a dozen men in military uniforms.
“This is not a coup d’etat,” he said. “This is a civic and military action to re-establish constitutional order. But more than that, it is to save the country from total destruction.”
In pictures: The crisis in Venezuela
The South American nation has for months been in the throes of a political crisis with protests that have left more than 100 dead, nearly 2,000 wounded and over 500 detained.
Last week, two opposition leaders were taken from their homes in the middle of the night by intelligence agents and hauled to prison.
It came days after the country’s president formed a legislative superbody internationally condemned as a power grab.
On Saturday, Mr Maduro’s new “constituent assembly” removed the chief prosecutor from her post and ordered her to stand trial, confirming opposition fears that it would use its powers to root out critics of the government.