Rice said today she is not ruling out an "encounter" with Mottaki at the conference of key powers, to be held May 3-4 in Egypt.
However, Rice said any discussions will center only on stabilizing Iraq and not broader U.S.-Iranian relations.
Iran said today it has decided to send a high-ranking delegation to next week's international conference on Iraqi security.
Foreign Ministry spokesman Mohammad Ali Hosseini said Mottaki will lead the delegation to the conference in Egypt.
Iran's presence is considered important because of the infuence Tehran has with Iraqi Shi'ites, whom the United States alleges it is supporting with arms and training.
The annoucement came as Iran's Supreme National Security Council Secretary Ali Larijani arrived in Baghdad. He held talks with Iraqi leaders, which were expected to focus on the coming conference. Iran says it has "some questions and ambiguities about the agenda."
The conference is to gather Iraq's neighbors as well as Egypt, Bahrain, and representatives of the five permanent members of the UN Security Council.