Venezuela's opposition says it will stage the "mother of all marches" on Wednesday, accusing President Nicolas Maduro of resorting to dictatorial measures to quash popular outrage over a deepening economic crisis.
"The use of public forces and arms against demonstrators should only be used after all mechanisms of negotiation are exhausted", Ortega Diaz said in the statement.
"We are concerned about that situation".
There are reports that a young protester is in a serious condition after being shot in the head in the San Bernardino area of the capital. There were no other details immediately available.
"The whole of Caracas will be held by the revolutionary forces", said lawmaker Diosdado Cabello, one of Maduro's most powerful allies. He says the boy died in the operating room as surgeons attempted to save his life.
"The U.S. government, the State Department have given the green light, the approval for a coup process to intervene in Venezuela", said Maduro, citing a State Department communique issued Tuesday titled "Non-Violence and Accountability During Protests in Venezuela".
They urged Venezuelan authorities to "guarantee the right to peaceful protest as enshrined in the constitution and to prevent any violent action against the demonstrators".
Venezuela has reiterated to the Organization of American States that it does not recognize the hemispheric group's resolution saying the South American country had violated constitutional order.
Julio Borges, center, president of the National Assembly and deputy of the Venezuelan coalition of opposition parties (MUD), tears a copy of a sentence of the Venezuela's Supreme Court during a news conference in Caracas, Venezuela, March 30, 2017. Maduro has repeatedly accused the United States generally, and former Vice President Joe Biden specifically, of organizing a right-wing coup against him.
It is a touchy date in Venezuela, where Chavez and Maduro have built a politics of populist, left-wing nationalism around the fight for independence from colonial Spain and around the hero of the struggle, Simon Bolivar. Reuters quoted Brazil's foreign minister as saying, "Brazil supports an honest and effective global political dialogue to guarantee the full restoration of democracy".
The volatile country is now braced for what Maduro's opponents vow will be the "mother of all protests" on Wednesday.
Opposition marchers included Liliana Machuca, who earns about $20 a month holding two jobs teaching literature. Her face was covered in a white, sticky substance to protect herself from the noxious effects of tear gas.
Many were state workers like Leidy Marquez, who was bused in from Tachira state, on the other side of the country, along with co-workers at state-run oil giant PDVSA. Venezuela's defence minister on Monday declared the army's loyalty to Maduro, who ordered troops into the streets ahead of a major protest by opponents trying to oust him.
Supporter of Venezuelan President Nicolas Maduro also took part in a large counter rally in the city.
Foreign Minister Delcy Rodriguez labelled the communique as "rude interference".
State ombudsman Tarek William Saab, the official in charge of human rights, said at the weekend that the siblings had received medical assistance.
Maduro also deployed the Venezuelan armed forces to the street on Sunday night, where they will stay for the duration of the marches.
The streets of Caracas have seen running battles pitting masked protesters hurling stones and Molotov cocktails against riot police firing tear gas, rubber bullets and water cannons.