"If today we were millions, tomorrow even more of us need to come out", said opposition governor and two-time presidential candidate Henrique Capriles, who last week was barred from running for office for 15 years.
Riot police fired tear gas to force back stone-throwing demonstrators as hundreds of thousands of people fed up with food shortages and demanding elections joined protest marches in Caracas and several other cities.
Tintori marched Thursday wearing a T-shirt with a posterized image of her jailed husband, political opposition leader Leopoldo Lopez.
In the capital, Caracas, anti-government protesters and police exchanged tear gas, rocks and Molotov cocktails.
"Twenty days of resistance and we feel newly born", opposition MP Freddy Guevara shouted.
"The opposition renewed the demonstrations quickly because they want to keep the momentum going", Al Jazeera's Daniel Schweimler, who has been denied access to report in Venezuela, said from Argentina's Buenos Aires.
But the move against GM, the U.S.'s biggest automaker, was a much more powerful statement, and could lead to a further erosion of relations between the two countries.
In its fourth quarter earnings of 2016, the firm stated that its South American area remains challenged due to political and macro-economic standpoints. This move seemed to aim at provoking the authorities of the United States and diverting attention from rising protests against Nicolás Maduro (President). That march was the largest and most dramatic the country has seen in years.
There were also late-night barricades and some looting in Caracas' middle class neighbourhood of El Paraiso on Wednesday night. Over 400 people were arrested during protests on Wednesday, rights group Penal Forum said.
The march followed a fortnight of violent protests triggered by a Supreme Court decision in March to assume the powers of the opposition-led Congress - which it quickly reversed under global pressure.
Mass anti-government demonstrations were held across Venezuela on Wednesday and Thursday.
Exxon Mobil sought arbitration after the government of President Hugo Chavez nationalized the company's oil project in the South American nation's oil-rich Orinoco region in 2007.
Movistar and Telefonica did not immediately respond to requests for comment. That effort ultimately faded amid protester fatigue and a heavy state crackdown. Among the victims were a 17-year-old boy and a 23-year-old woman, both shot in the head in separate incidents.
It hurts to see "our courageous young people" subjected to violence, tweeted human rights activist Lilian Tintori, adding, "We swear we will regain [Venezuela's] freedom". It later took the government to court.
Maduro critics increasingly doubt that the ruling Socialist Party, which was soundly defeated in 2015 legislative elections, will allow for free and fair elections.
Last year Greece's economy was unchanged.