President Maduro - a former bus driver and union leader who accuses foreign countries of "meddling" - is now visiting communist ally Cuba for a meeting of the ALBA bloc, which includes Venezuela's leftist allies in Latin America including Nicaragua, Bolivia and Cuba.
Several thousand demonstrators led by deputies including National assembly leader Julio Borges were attempting to march to the office of the country's human rights agency, when they were stopped by police forces, who used tear gas to disperse the crowds.
Here are some images.
On Saturday, thousands demonstrated against a ban from politics imposed on opposition leader Henrique Capriles.
"We need to get out on the street and fight, to tell these people we don't want them", said Maria Guedez, a 67-year-old homemaker carrying a sign that read, "No more dictatorship".
The move is not likely to have a major impact on the Venezuelan economy, which has already been crippled by shortages of food and medicine, power outages, and strikes.
He said he wanted elections "so as to hand a defeat to those people very soon, so that they will stop the rioting and violence; to respond to them with votes".
The opposition is demanding a date for gubernatorial elections that were supposed to take place a year ago, as well as a timeline for future elections including the presidential vote, which is constitutionally mandated for 2018.
Guevara called the president a "liar". The statement was vehemently protested by other OAS member-states, who accused the countries of bypassing OAS protocol to intervene in Venezuelan politics. "An 87-year-old woman died inside her apartment in Colinas de Bello Monte".
Mexico's foreign ministry underscored the "importance of achieving in the short term a national political accord that will allow Venezuelans to recover democratic normalcy".
Maduro was meanwhile in Havana for a meeting of foreign ministers of the leftist ALBA bloc, a Latin American group co-founded by his late mentor, Hugo Chavez.
Bolivia, Cuba, Ecuador, Nicaragua and several Caribbean countries were expected to issue a statement of support for Maduro at the meeting. "We can't accept a regime that is willing to sacrifice the lives of Venezuelans in order to perpetuate itself in power", he said in a video posted on his Twitter account.
Regional governorship polls were postponed indefinitely in December and municipal ones are due later this year amid a chaotic political struggle.