Fearing bloodshed and calculating that it would gain them nothing, the movement's leaders called off a day of mass protests, reflecting their increasing powerlessness against the government's military muscle.
"We have to expand social networks, websites, these are our best means," said Mir Hossein Mousavi, a former prime minister who maintains he was robbed of the presidency through fraud in the June 12, 2009, election.
"These work like an army. This is our army against their military force," he said on his website, Kaleme.com.
The retreat from Iran's streets and university campuses to the Web is certain to be seen as a victory for the ruling hard-liners and for the armed forces that preserved their grip on power with a harsh crackdown on postelection protesters.
The anniversary passed with no signs of major disturbances or sizable gatherings.
Witnesses reported sporadic but minor clashes at Tehran's Azadi Square between a few dozen protesters and anti-riot police swinging batons. Security forces were seen taking one person away near the entrance of Tehran University, where no gatherings were allowed to form, another witness said.
A small number of people were arrested in Tehran, the semiofficial ISNA news agency reported, quoting a top police official, Ahmad Reza Radan. The report did not elaborate.
Hundreds of police were deployed at main junctions in the capital. The government, which had warned that any unauthorized gatherings would be harshly confronted, said the extra deployments were part of regular movements in Tehran.
The scene was in stark contrast to a year ago.
Then, hundreds of thousands took to the streets to protest alleged fraud, which they said deprived them of a Mousavi presidency that might have brought a measure of political and social change. Mousavi had campaigned on promises of economic reform, freedom of expression and a review of laws that discriminate against women.
Abuses against detained activists — which the government at least partially acknowledged took place — pushed some opposition supporters to go even further and challenge the ruling clerical establishment itself. But trials — some of which have resulted in death sentences — and threats to put down unauthorized demonstrations have left the movement with nowhere to go.
Even on the Web, Iranian authorities chase them, blocking sites and jamming Internet and mobile phone service at times.
The tightening controls have led to criticism of what Mousavi on Saturday called "an inclination toward dictatorship" by Iran's leadership — a potent jab from a man once considered a regime insider and who played an active role in the 1979 revolution that brought clerical rule to Iran.
"Those at the top (of the ruling system) think they are special creatures of God almighty and that God pays special attention to (him); that whatever he says must be carried out ... and there is no belief in collective logic," Mousavi said, in an apparent reference to Supreme Leader Ayatollah Ali Khamenei.
Mousavi pledged Saturday to continue a peaceful struggle against the government of President Mahmoud Ahmadinejad, whose rule has coincided with a sinking Iranian economy and growing international isolation as a result of the defiance over the country's nuclear program.
"We need to spread awareness," Mousavi said. "This is the point of vulnerability of those who are after despotism. If awareness is spread, there will be a huge popular force behind the demand for change."
He and fellow opposition leader Mahdi Karroubi have declared the price of more direct confrontation to be too high.
The opposition says at least 80 protesters were killed in last year's street clashes. Authorities have put the figure at around 30.
Mousavi's statement Saturday said that while the opposition "may put off its presence in one arena," it will persevere through other ways.
He urged Iranians to distribute films, photos, video clips and cell phone footage of what is really going on in the country.
That has been the opposition's strategy for some time now, and it has yet to bring tangible gains. Dozens of Web posts and proclamations against Ahmadinejad and the ruling system are issued each day — but all they amount to is words against muscle.
The past year, however, has not been without moments of deep change for Iran — a year ago, it would have been unthinkable to chant slogans against Khamenei, who has the final say on all matters in Iran. The chants are now common and have punched holes in the political firewall that once separated the theocracy from the people.
At the same time, Iran's rulers have retrenched and handed more control to the Revolutionary Guard, resulting in a far more aggressive hand at home and a less compromising attitude aboard — including a hard line over Iran's nuclear program, which brought a new, fourth round of U.N. sanctions on Wednesday.