Haleh Esfandiari , the director of the U.S. Woodrow Wilson International Center for Scholars' Middle East program, was arrested in Iran on May 8.
Iran also confiscated the passport of Farda reporter Parnaz Azima during a visit to Tehran in January, and has prevented her from leaving.
State Department spokesman Sean McCormack did not refer to the women by name, but said two women, a scholar and a journalist, were among Iranian-Americans who were not allowed to leave
'No Threat' To Iranian Government
He said Washington wanted to see them returned to their families.
"These are grandmothers. I don't think that they're going to shake the foundations of the Iranian regime," McCormack told a news briefing in Washington. "These are people who don't pose any threat to the Iranian government and, in fact, symbolize the kind of people-to-people interaction that we want to encourage."
Esfandiari, who in the past has specialized in women's issues, was taken to Evin Prison in Tehran on May 8, after being regularly interrogated about her academic work and prevented from leaving the country since December, the Woodrow Wilson Center said.
Azima, a correspondent for Radio Farda in Prague, had her passport confiscated in January when she traveled to Tehran to visit her sick mother.
(with material from Reuters, dpa)