The four join nine other Baha'is in jail in Iran and six of those 13 are on death row, spokesman James Foley said. The people arrested were members of the Baha'i Institute of Higher Education, a self-help university founded in 1987 after Iran made it harder for Baha'is to attend public universities.
Baha'is in France said earlier this month the Iranians had cracked down on the institute in 14 cities, arresting 32 people and breaking into and looting many homes.
Foley said the Iranians had initially arrested at least 36 people in raids on more than 500 homes and office buildings owned or rented by Iranian Baha'is.
They confiscated materials that had no political or religious content, such as dentistry and accountancy textbooks, as well as some laboratory equipment, he added.
"We urge the government of Iran to eliminate restrictions on the practice of religion and to recognize and uphold the fundamental human right to freedom of conscience and belief," he said. He also urged Iran not to carry out the executions.
The Baha'i religion, an offshoot of Islam, originated in Iran 150 years ago. It says it has 6 million members, including 350,000 in Iran, where it is officially considered "a misleading and wayward sect."