The country's chief prosecutor reported Thursday on Twitter that a 16-year-old was killed at a protest in the capital overnight and a 23-year-old man died at a demonstration in Merida state.
They expect President Donald J. Trump and his administration will impose economic sanctions "that materially increase the risk of a debt default" and undermine Maduro.
More protests and a national strike are planned ahead of Sunday's vote for a Constituent Assembly.
The 48-hour strike announced by opposition leaders a few days ago began on Wednesday. It's the only way to show we are not with Maduro.
"We will be relentless if they try to generate a process of violence in order to stop that which can not be stopped", he said. But hooded youths clashed with soldiers firing tear gas in various places including Caracas.
The main central trade unions have lent their support to the mobilization launched by the opposition, the trade union leader Marcela Maspero, speaking of the "strike history that tries to stop the tyranny".
Later on Monday, rights group Penal Forum reported that lawyer Angel Zerpa, one of the new Supreme Court magistrates sworn in by the opposition in defiance of the government, had been charged with treason in a military court.
One of the USA officials warned the sanctions were just an initial round and the administration was readying tougher measures.
There's been concern that sanctioning the country's oil industry - where it makes 95 percent of its income - would make matters even worse for the Venezuelan people.
One option might include imposing restrictions on the oil that the USA imports from Venezuela.
Venezuela's economic collapse has led to chronic shortages of sanitary products such as toilet paper and toothpaste, as well as other basic resources such as food, medicine, and electricity.
He calls on the Venezuelan army not to deploy Sunday to protect the vote.
"Congratulations for these imperialist sanctions", he said, before handing out the symbolic swords.
"And the weak excuses they presented last night rejecting without evidence, in no way discredit, by far, a piece of evidence as strong as the opinion from the very mouth of the director of the Central Intelligence Agency, and second, the historical record of both those countries", he said.
Among those sanctioned is Tibisay Lucena Ramirez, head of the National Electoral Council, which Maduro controls. Finally, once they have succeeded in each one of these steps and the global community reacts, populist governments become dictatorships.
President Trump has said the United States is willing to take further action if Maduro's regime continues down the same path and follows through with the election. The opposition has also long accused PDVSA of being a nest of corruption.
The U.S. sanctions target four senior Venezuelan officials that the U.S. says were promoting the July 30 election or undermining democracy in Venezuela, five others responsible for violence and repression, and four Venezuelans linked to the state oil company and other government-run entities.
According to the press release, "All assets of these individuals subject to USA jurisdiction are frozen, and US persons are prohibited from dealing with them".