The Baha'i community representative to the United Nations in Geneva, Diane Ala'i, told RFE/RL that the government is trying to link Baha'is to the recent demonstrations.
Clashes during the December 27 protests on the Shi'ite Ashura holiday left at least eight demonstrators dead. Mass arrests are said to number well into the hundreds or higher.
Ala'i said the 13 Baha'is were arrested on January 3.
She said "they have been asked to sign a commitment letter promising not to attend protests in the future. However, they did not attend the [Ashura day] rally."
Ala'i said that although three of those arrested have been released, 10 remain incarcerated at Evin Prison in Tehran.
She said that there are a total of 48 Baha'is in Iranian jails.
The arrests come as seven Baha'i community leaders are set to stand trial on January 12. They face charges of espionage and propaganda against the Islamic Republic.
The Baha'i faith began in 19th century Iran, and currently has an estimated 5 million followers worldwide. While Baha'is regard their faith to be within the tradition of Abraham, Moses, Buddha, Jesus, and Muhammad, Iran's Shi'ite government regards Baha'ism as Islamic heresy.
There are some 300,000 Baha'is in Iran, a community that human rights groups say has faced serious repression under the Islamic republic.
Baha'i community representative Ala'i believes the latest arrests of Baha'is are designed to tarnish the reputation of their community and hurt the prospects of the Baha'i leaders at their upcoming trial.