His death marked the sixth fatality in nearly three weeks of escalating protests.
In Washington, administration officials are anxious the Venezuela government is working to suppress the opposition.
"The US government, the state department, have given the green light, the approval for a coup process to intervene in Venezuela", Maduro said in a televised address Tuesday, according to The Guardian.
A demonstrator throws a tear gas canister back at the police during a rally against Venezuelan President Nicolas Maduro, in Caracas on April 19, 2017.
Records from Trump's inaugural committee released Wednesday show that Citgo Petroleum, a USA affiliate of Venezuela's state oil company PDVSA, was one of the biggest corporate donors to the swearing-in ceremony.
One protester, Helma Mendoza, said she joined "the mother of all marches", organized by leaders of the center-right political opposition, because of Venezuela's tattered economy and the resulting strain on her family and the broader society.
"I am motivated by the hunger that we are going through ..." "We'll see who tires out first". "This cheating government has betrayed us, the people, the children in the family".
"Today the people stood by Maduro!" the president said, blasting his rivals as "anti-Christs".
Maduro rallied his supporters to participate in a counter march, and thousands turned out Wednesday wearing red clothing that marked them as Chavistas.
There aren't many reasons to sing and dance in Venezuela today.
Analysts say there is less likelihood of a coup against Maduro because Chavez launched a broad purge of the armed forces following his brief ouster.
Tens of thousands of protesters made an unsuccessful attempt to march to downtown Caracas as security forces fired tear gas and rubber bullets into the crowd.
At least five deaths and hundreds of arrests have been blamed on the response to paralyzing protests that were triggered by the Supreme Court's shock decision three weeks ago to strip the opposition-controlled legislature of its last remaining powers.
The crisis escalated on March 30, when the Supreme Court tried to take over the powers of the National Assembly, the only lever of government Maduro and his allies do not control.
Opponents of President Nicolas Maduro called on Venezuelans to take to the streets on Wednesday for what they dubbed the "mother of all marches" against the embattled socialist leader.
The court partly backtracked after an worldwide outcry, but the tension only increased when authorities slapped a political ban on opposition leader Henrique Capriles on April 7. But you'd never be able to tell from the information published by Venezuelan official sources - including the vice-president, Telesur, and VTV - that have been reporting exclusively on pro-government rallies in which large numbers of people participated, including some who sing and dance "in defense of peace".
Further spurring outrage was a decision by the national comptroller's office earlier this month to disqualify Capriles from holding office for 15 years, dashing his hopes for the presidency. Economic pressures have mounted in recent years, especially since the price of oil - Venezuela's chief export - began falling in 2014. Venezuelans face chronic, severe shortages of food, medicine and other basics in what once was Latin America's wealthiest country.
Maduro this week said he was dramatically expanding civilian militias created by Chavez and giving each member a gun.
The statement, by spokesman Mark Toner, urged nonviolent demonstrations. He also said authorities in recent hours had rounded up unnamed members of an underground cell of conspirators at Caracas hotels, including some armed people who were allegedly planning to stir up violence at the march.