US President George W Bush has said he is willing to help European countries in their negotiations with Iran over its nuclear programme.
Tehran says its nuclear activities are peaceful
Mr Bush said he had told the Europeans that the US was looking at how it could help move the process forward.
The European plan could offer Iran economic and trade incentives if it abandons its nuclear programme.
The US has accused Iran of secretly trying to develop nuclear weapons - a charge Tehran denies.
"I have told our European friends who are handling the negotiations on behalf of the rest of the world that we want to help make sure the process goes forward, and we're looking at ways [to do this]," Mr Bush said.
The announcement came after a meeting of the UN nuclear watchdog, the IAEA, ended on Thursday.
During the meeting, the EU and the US criticised Iran for its lack of co-operation and failing to give UN inspectors full access to its nuclear sites.
Diplomats told reporters that a review read at the meeting said that Iran was using reinforced materials to build deep tunnels to protect nuclear material in case of a military attack.
The IAEA faulted Iran for starting work on the tunnel at Isfahan without informing the agency.
IAEA spokesman Mark Gwozdecky said that Iran needed to improve its openness about its nuclear activities.
So far, the US has adopted a more confrontational approach than the Europeans, threatening to have Iran referred to the UN Security Council for possible sanctions.
Talks between Europe and Iran resume in Geneva next week.