In remarks published on his Web site late Sunday, Mohsen Rezaei urged the other two defeated candidates - both of them reformists - to drop their push for a new vote and work with President Mahmoud Ahmadinejad.
The former commander of the powerful Revolutionary Guard may be trying to position himself as a neutral figure in the dispute who could work to bring Iran's divided camps together.
The two other defeated candidates, including main opposition leader Mir Hossein Mousavi, have charged that Ahmadinejad's landslide re-election was the result of fraud and want the results scrapped. The official outcome of the June 12 vote triggered days of street protests. Authorities responded with a violent crackdown and roundups of activists, academics, journalists and lawyers.
The election dispute also exposed rifts within Iran's clerical establishment.
"A continuation of the current situation will drive us toward disintegration," Rezaei said.
Rezaei also accused the United States and Israel of plotting against the country. Government officials have also accused foreign powers - the U.S. and Britain, in particular - of fomenting the unrest in the streets.
"They - the U.S and Israel - plotted this disintegration to weaken Iran and make it surrender through sanctions or attack" Rezaei said.
He also had words of rebuke for the government, saying it should have differentiated between protesters and what he called "counterrevolutionaries" and "violators."
Both sides, he said, were providing opportunities for Iran's enemies through their struggle.
"I believe the continuation of the way of some political activists will drive us backward and toward failure and the method of some others will take us to the precipice," Rezaei said.
He added, however, that "the damage by both sides is still repairable" and said Iranians could learn from the experience for the sake of the country's future.
On Saturday, one of the disputes between the two sides was settled by the Expediency Council, a body that arbitrates disagreements between parliament and the Guardian Council, whose powers include overseeing elections.
The Expediency Council - which is headed by a bitter enemy of Ahmadinejad, former President Akbar Hashemi Rafsanjani - approved a bill in parliament that bars members of other branches of government from serving in the Guardian Council.
The Guardian Council's membership includes three members of Ahmadinejad's administration and judiciary, a fact cited by the opposition in its arguments that the council is not impartial.
Much of the post-election intrigue has focused on Rafsanjani and what role he might have played in the opposition to Ahmadinejad's re-election.
Iranian media reported that the powerful cleric, who also leads a body that has the power to remove the supreme leader, will deliver the sermon at this week's Friday prayers for the first time since the election.
That signals that Rafsanjani remains influential in Iran's clerical establishment, which is divided over the election.
Ruling clerics have called the election "pure" and "healthy," while others in the religious center of Qom have refrained from congratulating Ahmadinejad and have even openly supported Mousavi.
"A political system based on force, oppression, changing people's votes, killing ... and using Stalinist and medieval torture ... is condemned and illegitimate," he said.
He made the comments during a clerical debate Friday about the qualifications for a supreme leader. He also challenged the use of detainees' confessions, which critics say are being coerced through abuse.
"According to the teachings of the prophet and his descendants, confessions in jail have no religious or legal validity and cannot be the criterion for action (against the confessor)," he said.
Montazeri was the heir apparent to the late Ayatollah Ruhollah Khomeini until falling out of favor with the ruling clerics in 1989 by questioning their almost limitless powers. Montazeri spent five years under house arrest in the 1990s in the city of Qom.