The State Department said Washington hoped that body would adopt "the strongest possible resolution" calling for Iran to comply with its commitments under the nuclear Non-Proliferation Treaty (NPT).
But spokesman Richard Boucher said the United States would not press the IAEA board to refer the Iran matter immediately to the UN Security Council, which could impose sanctions against the Islamic republic.
"We've been working actively with other members of the international community to build support for the strongest possible resolution," he told reporters.
"From our discussions to date, we believe that almost all members of the (IAEA) board share our grave concerns about Iran's activities," Boucher said.
He noted that IAEA chief Mohamed ElBaradei had said earlier Monday at the opening of the board's meeting at its Vienna headquarters that Iran must address questions about its nuclear program.
ElBaradei also said Iran, a member of the 35-nation board, should also sign an additional protocol to the NPT which would give the UN's nuclear inspectors the power to make unannounced checks of its atomic facilities.
The United States claims Iran is hiding a secret nuclear weapons program by ostensibly developing civilian atomic energy facilities, an allegation Tehran has vehemently denied.
The IAEA board is meeting in part to consider a report from ElBaradei on the Iranian program which Washington says provides "compelling evidence" that Iran is in violation of the NPT and is refusing to cooperate with international inspectors.
The United States, Britain and Canada are sponsoring a IAEA resolution demanding Iranian compliance and which they hope the board will adopt unanimously.
But diplomats in Vienna have said that while Washington would like to see a deadline set for Iranian compliance, it was willing to let this point drop in the face of opposition from non-aligned countries, and apparently Russia.
Such a deadline could be used as a trigger for referral to the UN Security Council.
Boucher indicated that the United States would not demand a timeline for referral to the council although he stressed that it would at some point be the appropriate forum to look at the Iranian situation.
"It is still our view that this is a matter that needs to be taken up at the appropriate time by the Security Council," he said.
"When and how (IAEA action) will lead to a possible referral to the Security Council, I think, may not be addressed in this particular resolution," Boucher said.