The US Secretary of State has said America stands by opposition supporters in Iran who sought to protest on Monday.

Hillary Clinton called on Tehran to grant its citizens the same freedoms that were recently won by protests in Egypt.

"Let me, clearly and directly, support the aspirations of the people who are in the streets in Iran today," Clinton told reporters after meeting with the Republican speaker of the House of Representatives.

"What we see happening in Iran today is a testament to the courage of the Iranian people, and an indictment of the hypocrisy of the Iranian regime -- a regime which over the last three weeks has constantly hailed what went on in Egypt," Clinton said.

"We wish the opposition and the brave people in the streets across cities in Iran the same opportunities that they saw their Egyptian counterparts seize."

Clinton spoke after an Iranian opposition website said dozens of people were arrested on Monday while taking part in a banned rally in Tehran to support popular uprisings which toppled the governments in Egypt and Tunisia in recent weeks.