Within seconds, Maduro said he heard a second explosion and pandemonium broke out. "Today, they attempted to assassinate me".
The US State Department dismissed the accusations while rights group Venezuela Justice said a subsequent purge of the country's armed forces resulted in 150 people being jailed "for political reasons".
The alleged assassination attempt came days after the Colombian president told AFP that Maduro's days are numbered and "that regime has to fall".
Although details were sparse and confusing, Venezuelan president Nicolas Maduro survived what appears to be the first assassination attempt using commercially available drones.
"We warn that this confused event could be used as an excuse to repress the constitutional rights of the people to continue protesting for the defence of their rights", the statement said late Saturday.
Just over a year ago, Maduro claimed a police helicopter had fired grenades at the Supreme Court in a "terror attack" that caused no injuries or damage and was dismissed by the opposition.
One showed a cellphone video of a drone hovering over a residential street two blocks away and then crashing into a building.
Meanwhile, an obscure four-year-old Venezuelan group calling itself the "National Movement of Soldiers in T-shirts" has claimed responsibility for the blast, explaining that their two drones were shot down by government snipers.
In an address to the nation Saturday night, a visibly shaken Maduro recalled seeing a "flying device" that exploded.
Rodriguez said there was "an explosive charge. detonated close to the presidential podium" and in several other spots along the parade held in central Caracas.
Reverol said he doesn't rule out further arrests.
U.S. national security advisor John Bolton insisted Sunday that there was "no United States government involvement" and even suggested on "Fox News Sunday" that the incident could have been "a pretext set up by the regime itself".
"If the government of Venezuela has hard information that they want to present to us that would show a potential violation of United States criminal law, we will take a serious look at it", he added. The authenticity of the message could not be independently verified, and the organization did not respond to a message from the AP.
Germany said merely that it was "closely following developments on the ground", while Portugal opined that the crisis in Venezuela could be overcome by "dialogue and national consensus" in line with "democratic principles". Oscar Perez and several comrades were later killed in a gun battle after over six months at large.
Images on social media showed officers surrounding Maduro with what appeared to be a black bulletproof shields as they escorted him from the site.
Maduro said the incident had left him convinced of the military's support and undeterred in carrying forward the torch of Chavez's revolution. "But there was a shield of love that always protects us".