The US secretary of state is seeking new funds for a policy aimed at putting pressure on Iran's government and promoting internal opposition to it.
Rice says she wants to support the aspirations of Iranians
Condoleezza Rice asked Congress for $75m to increase TV and radio broadcasts and fund dissident groups.
Correspondents say the move comes amid US fears that the world community will not countenance tough action over Iran's nuclear ambitions.
Critics of the US plan say the funds are not enough to make a difference.
Former Clinton administration official Martin Indyk told the Washington Post newspaper that the groups the US wants to fund have little support on the ground and have been unable to challenge the Islamic government in Iran.
Ms Rice is planning to visit the Middle East next week to discuss the Iranian issue with regional leaders.
Appearing before the Senate Foreign Relations Committee on Wednesday, the secretary of state outlined a two-track approach, involving concerted international pressure to deter Iran from seeking nuclear weapons and an attempt to change the country from within.
FUNDS FOR IRAN PROGRAMME
$50m - to introduce 24-hour Farsi broadcasts into Iran by US government TV and radio
$15m - for trade unions and human rights groups
$5m - for student exchanges
$5m - to set up independent websites, TV and radio stations in Farsi
"The United States will actively confront the policies of this Iranian regime, and at the same time we are going to work to support the aspirations of the Iranian people for freedom in their own country," she said.
The funds being sought, though not a substantial amount, are a huge increase on the $10m already budgeted to support dissidents in 2006.
Most of the money, if approved, will go towards stepping up broadcasts in the Farsi language, with a smaller amount earmarked for help to human rights and other groups.
Ms Rice added that by resuming small-scale uranium enrichment last week the Iranians had "crossed a point where they are in open defiance of the international community".
Iran's decision came in response to a resolution by the International Atomic Energy Agency to report Iran to the UN Security Council.
The move could lead eventually to sanctions against Iran, but it is far from clear whether Russia or China, who backed the resolution, would agree to this.
BBC diplomatic correspondent Jonathan Marcus says that it is this uncertainty which has led the US to shift its policy and seek to change Iran from within.