Critics of the verdicts accuse the authorities of persecuting citizens willing to campaign for social rights, and using the suspended sentences to ensure that detractors remain silent.
Nasrin Afzali, Nahid Jafari, and Minoo Mortazi were found guilty of acting against national security, disrupting public order, and refusing to follow police orders. All the charges stem from their participation in a political rally outside a Tehran courtroom in March 2006.
A fourth female activist, Zeinab Payghambarzadeh, who attended the same rally, was given a two-year suspended prison term after being accused of similar charges.
The sentences will only be carried out if the women are found guilty of another crime within two years. All four women intend to appeal the verdicts.
Zahra Arzani, a defense lawyer for Jafari, told Radio Farda that such sentences are intended to humiliate human rights activists across the country.
"The feminist movement's work and demands are entirely peaceful," Arzani said. "Their latest project -- the One Million Signatures Campaign -- is also a peaceful project that involves talking to people in person. It is not a crime."
Arzani added that "people who take part in these projects should be appreciated and shown gratitude for doing this work, instead of being sent to prison and beaten up."
Jafari said that by gathering outside the court in 2006, she and the other women were protesting the trial of fellow rights activists. But she said the police disrupted the peaceful rally, beating up and arresting dozens of demonstrators.
She told Radio Farda that the court has yet to respond to a formal complaint that she filed about abusive behavior by the police officers.
"Back then, I was beaten up badly. I had bleeding, and my hearing ability was impaired for some time afterwards," Jafari said. "They inflicted serious injury on me, but I still haven't got any response to my complaint."
Afzali, for her part, said that she does not understand why human rights activists should be arrested and punished.
All the women are members of the One Million Signatures Campaign, a nonpolitical movement that seeks to change what it calls discriminatory laws in Iran, including laws on inheritance, divorce, and child custody.
Campaign members want to gather 1 million signatures from Iranians and ask the parliament to abolish those laws, which the campaign says treat women as "second-class citizens."
Some 43 of the campaign's members have been arrested since it was launched in August 2006, most of them subsequently charged with acting against national security.
One campaign member, Khadija Moghaddam, arrested earlier this month, is awaiting trial after failing to pay $110,000 in bail that a Tehran court had set for her release.
Iranian-born human rights activist Mehrangiz Kaar said that the authorities obviously feel threatened by human rights and feminist activities, and that they fear such activities might expand around the country as a part of a greater social rights movements.
Kaar told Radio Farda that Tehran "wants to keep all these rights activists silent -- that's why the feminists have been handed suspended sentences."
According to Kaar, the authorities hope that with suspended jail sentences hanging over their heads, the women will not take any further risks by getting involved in rights-related activities.
Iran denies Western allegations of discrimination against women.
RFE/RL correspondent Farangis Najibullah contributed to this report