The US Commission on International Religious Freedom, a non-partisan official body that advises the US government, criticised Iran last week for "ramping up vilification" of Bahais in light of recent unrest.
President Mahmoud Ahmadinejad's disputed June re-election triggered a wave of opposition protest amid charges that the vote was marred by massive fraud.
At least 300 of those arrested during protests are still held in Tehran, police say.
