About half them were detained when trying to march to offices of the electoral authority in Caracas on Thursday, said Daniel Ascanio, student leader from Simon Bolivar University.
"There is no reason for them to be detained," he said, insisting they had been protesting "peacefully."
Opposition demonstrators accuse the security forces of repressing and jailing opponents.
Judicial NGO Foro Penal says 3,500 people have been arrested in the unrest. Prosecutors say 82 people have been killed.
The opposition is demanding elections to replace President Nicolas Maduro, blaming him for a desperate economic crisis. He says the crisis is a US-backed conspiracy.
Attorney General Luisa Ortega, the most high-profile official to break ranks with Maduro, announced a fresh move in her legal challenges against him on Friday.
She filed charges against the head of the state intelligence service, Gustavo Gonzalez Lopez, for alleged human rights violations.
US carrier United Airlines ran its last flight from Venezuela on Friday. It said it was suspending the Caracas-Houston route due to financial problems in the country.
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