Her lawyer, Gholam Ali Riahi, told the semiofficial ISNA news agency that the charges against Faezeh Hashemi were related to interviews she gave to news websites.
Hashemi appeared at opposition protests after the disputed June 2009 presidential elections and was briefly detained in February.
Riahi said Saturday he had asked the court to give him three days to prepare a final defense.
Meanwhile, candidates started registering Saturday to stand in Iran's March legislative elections in a process vetted by the Guardian Council, the Islamic republic's electoral watchdog.
"We recommend to candidates to come forward to serve the people and to keep the success of the Islamic revolution in mind," the ministry's website quoted Interior Minister Mostafa Mohammad Najjar as saying.
Registration will continue until Dec. 30, but the Interior Ministry urged would-be candidates not to wait until the last day.
The Guardian Council, made up of preachers and jurists, determines which applicants can be candidates in the election to the 290-seat Parliament. It is also responsible for endorsing the final results of the March 2, 2012 elections.
Candidates are required to be Iranian citizens aged between 30 and 75 who are loyal to the constitution, including its recognition of the absolute authority of supreme leader Ayatollah Ali Khamanei.
Iran's current legislature is dominated by conservatives, with only around 60 reformists in the house.
The parliamentary speaker, Ali Larijani, has repeatedly criticized the policies of President Mahmoud Ahmadinejad, especially on the economy.
The March poll will be the first since the 2009 presidential election which saw Ahmadinejad announced the winner over opposition claims the vote was rigged, triggering widespread mass protests.