Many reform-minded Iranians say they will snub the election over crackdowns by Iranian authorities and the decision to keep former President Akbar Hashemi Rafsanjani from the ballot.
Rafsanjani's stature rose sharply with liberals after he criticized hard-line tactics used in 2009 against protesters following the disputed re-election of President Mahmoud Ahmadinejad, who cannot run again this time because of term limits.
A Thursday report by the pro-reform Etemad newspaper quotes Rafsanjani as saying that people "should not boycott" the vote.
Several other newspapers reported similar comments.
Six candidates are on Friday's ballot, including former nuclear negotiator Hasan Rowhani, a close ally of Rafsanjani who is backed by reformist leaders.