Reiss, who has been out of jail on bail and staying at the French embassy, was arrested in the aftermath of the June 12 vote in which Mahmoud Ahmadinejad was re-elected as president.
She was accused of taking part in a Western plot to destabilise the Iranian government and was put on trial in August charged with acting against national security.
A judgement in the case had been expected in January, after Reiss had made four court appearances, but the verdict was put off.
Her case has raised tensions between France and Iran, with Paris saying that Reiss was innocent and demanding her immediate release.
Reiss was arrested in Tehran in July as she prepared to leave Iran after working at the University of Isfahan for five months.
She was among thousands of people detained over widespread post-election unrest, which was sparked after defeated presidential candidates said that the polls had been rigged.
The government has denied the claims.