Akbar Hashemi Rafsanjani, a former president who sits on two powerful clerical ruling bodies, made the comments during his sermon before tens of thousands of opposition supporters, with opposition leader Mir Hossein Mousavi sitting in the front row.
The opposition packed the prayer hall to make a show of strength at the weekly Islamic prayers, which broadcast live on radio and are one of Iran's most important and symbolic political platforms. It was Rafsanjani's first time delivering the sermon since the June 12 election. In recent weeks, hard-line clerics have been using the sermon to tell Iranians to fall in line behind Supreme Leader Ali Khamenei and accept the election victory of President Mahmoud Ahmadinejad.
Rafsanjani urged unity and appeared to blame hard-liners for disrupting unity by not listening to the controversy over the election, which was declared a victory for Ahmadinejad but which Mousavi claims to have won.
"Doubt has been created (about the election results)," Rafsanjani said. "There are two currents. One doesn't have any doubt and is moving ahead with their job. And there are a large portion of the wise people who say they have doubts. We need to take action to remove this doubt."
He said the turmoil following the elections "was a bitter period ... all were the losers." He criticized hard-liners for the crackdown on postelection protests, saying they should show sympathy for those arrested.
"Sympathy must be offered to those who suffered from the events that occurred and reconcile them with the ruling system. This is achievable. We need to placate them," he told the worshippers in the Tehran University prayer hall.
"It's not necessary ... to keep individuals in jail. Let them join their families. We should not let enemies criticize or laugh at us ... for keeping our people in jail," he said.
Rafsanjani suggested that Iran's state-controlled broadcasters also played a role in keeping the public dialogue stiffled following the election.
Multiple reports on Twitter and Facebook Friday afternoon said large groups of protesters were heading toward state-run television network IRIB and the Evin prison in Tehran's northern suburbs.
CBS News correspondent Elizabeth Palmer, one of the last Western journalists to be kicked out of Iran in the wake of the election, says Evin is a feared symbol of the hard-line government's authority in the capital city. Many of the political prisoners arrested during the crackdown will be housed within its walls.
Mousavi and his supports say Ahmadinejad's victory was fraudulent, and hundreds of thousands marched in the streets in the weeks after the election in support of him. But Supreme Leader Ayatollah Ali Khamenei, who sits at the top of Iran's clerical leadership, declared the results valid and ordered a stop to protests. Police, elite Republican Guards and Basiji militiamen launched a fierce crackdown on protesters in which hundreds were arrested and at least 20 killed - though human rights groups say the figure could be several times that official toll.
The opposition has managed to hold only one significant protest since - on July 9. But they are hoping their mass turnout at Friday's prayers will prove their staying power.
Tens of thousands - mostly pro-opposition but also some government backers - packed the prayer hall and shouted competing slogans. Hard-liners made traditional chants of "death to America," while opposition supporters countered with "death to Russia" - a reference to government's ties to Moscow. Many pro-reform worshippers wore green headbands or wristbands or had green prayer rugs - the opposition movement's color.
At the same time, thousands more opposition backers were heading toward Tehran University for a planned rally outside the campus after the prayers, raising fears of a confrontation with security forces or with hard-line militiamen, witnesses said.
Near the university gates, police fired tear gas at Mousavi supporters as they headed for the prayers, witnesses said. They spoke on condition of anonymity fearing government retaliation.
Two pro-reform Web sites reported that a prominent women's rights activist, Shadi Sadr, was beaten by plainclothes militiamen and taken away as she headed toward Tehran University. Sadr was forcible pushed into a car and taken to an unknown location, Mousavi's Web site www.mowjcamp.com and a women's activists site www.meydaan.com said.