Nabavi, a senior official from the Organisation of Mujahedeen of the Islamic Revolution party, had been sentenced to six years in prison for his part in protests against President Mahmoud Ahmadinejad's re-election.
The former deputy parliament speaker was released for 10 days on November 25 on a surety of 800,000 dollars pending a possible appeal.
"Today, as his 10-day leave ran out, Nabavi went to the revolutionary court… and he was told to go back to Evin prison," the party said in a statement posted on its website.
"He was told he has not observed necessary things during his leave, met with people outside his family, and made certain comments in these meetings apart from the usual greetings," it said, without elaborating.
In comments attributed to Nabavi after his release, he was quoted as saying arrest warrants for post-vote detainees were issued by an intelligence body several days before the June 12 election.
Iran cracked down on opposition supporters shortly after anti-Ahmadinejad protests broke out on Tehran streets and scores of senior reformist politicians and journalists were rounded up as well as thousands of protesters.
Several reformists have been jailed for several years having been found responsible for instigating the demonstrations.
Opposition leaders have denounced the proceedings as "show trials" and vowed to keep challenging Ahmadinejad, whose re-election they say was the result of large-scale rigging.
