"This is a dictatorship!" she denounced, while promising to continue "to fight for freedom and democracy in Venezuela".
Also on Saturday, South American trade bloc Mercosur indefinitely suspended Venezuela, adding to global pressure on Maduro to dismantle the newly created assembly and restore democracy.
He was first arrested in 2014 and released to home detention last month.
Another high-profile dissident, Antonio Ledezma, 62, was released back to house arrest Friday after being hauled away the same day as Lopez. Following their arrests the Venezuelan Supreme Court alleged that they had been planning to flee, either into hiding in Venezuela or overseas.
They also fear persecution should the opposition take over.
Venezuelan security forces have taken up position outside the office of the country's chief prosecutor.
"Do you know what they are trying to do?"
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Over eight million people voted in Venezuela's ANC election on July 30 - a turnout of over 41 percent, according to electoral authorities - to choose from 6,120 candidates for the 545-member ANC in a mass display of support for a peaceful resolution to the crisis in the country. It can rewrite the constitution, re-arrange state institutions and allow Maduro to rule by decree.
Authorities said the men were mercenaries working for a USA -backed opposition to bring down almost two decades of Socialism in oil-rich Venezuela, raising the specter of a further government crackdown on dissent in coming days. The captured subjects confessed to having been hired in the states of Zulia, Lara and Yaracuy by activists of the Venezuelan extreme right (the opposition) in connection with foreign governments, the Maduro Regime claimed.
Former Foreign Minister Delcy Rodriguez was elected President of the Constituent Assembly.
"We are saying: Stop with this!"
In a video posted online, Temer says "there is no more space for non-democratic alternatives in South America".
The Paramacay base, surrounded by a residential neighbourhood in Valencia, is one of Venezuela's largest and houses some of the country's most important armaments, including Russian-made tanks.
The measures adopted expand on previous sanctions against Venezuela, which had been temporarily suspended from the bloc in December.
During just the first six months of this year, 1,420 Venezuelans have sought asylum in Mexico, a almost four-fold jump compared to the 361 total Venezuelan asylum applicants for all of 2016.