Maduro's opponents and political analysts alleged a coup after the Supreme Court took over powers from the legislature and removed lawmakers' immunity.
International powers condemned the moves, which gave the socialist president control over the only major state institution that still had been out of his grasp.
But Maduro said in a speech to cheering supporters yesterday "In Venezuela, the constitution, civil, political and human rights and people power are in full force."
She branded the rulings a "rupture of constitutional order," in a surprise declaration on state television which drew applause from the crowd.
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Coming from a staunch supporter of Maduro's late predecessor Hugo Chavez, it was the strongest sign of divisions in the government camp since its standoff with the center-right opposition started in January 2016.
Maduro responded to Ortega in his speech by vowing "through dialogue and the constitution, to resolve the impasse" between the attorney general and the court.
The Supreme Court, which has staunchly backed Maduro through an economic and political crisis, assumed the powers of the National Assembly on Wednesday.
The legislative speaker, Julio Borges, called on the military and other institutions to follow Ortega's example and speak up against Maduro.
Street protests erupted for a second day yesterday in Caracas. Students marched on the Supreme Court, where they scuffled with soldiers.
Protesters also blocked streets in the working-class Petare neighborhood, and opposition lawmakers clashed with Maduro supporters downtown.
Many observers have said the Supreme Court's move amounts to a coup. The government rejected that accusation yesterday, lashing out at its critics as "imperialists."
The head of the Organization of American States called for the regional group's permanent council to hold crisis talks on the situation.
South American regional bloc Mercosur -- which suspended Venezuela in December -- will also hold crisis talks today, Argentina announced.
The opposition Democratic Unity Roundtable (MUD) won a landslide in legislative elections in December 2015.
The opposition has called for more street protests today.