U.S. Secretary of State Hillary Clinton says any overtures Washington makes to Iran will be done in consultation with its Middle East allies.
Her remarks Monday in Sharm el-Sheikh, Egypt, follow comments from a State Department spokesman that Clinton had been trying to assure her counterpart from the United Arab Emirates about U.S.-Iranian relations.
Arab neighbors have expressed concern about a possible regional ascendancy of non-Arab Iran.
The U.S. official, speaking on condition of anonymity, said Clinton had privately downplayed the possibility of Iran taking the United States up on an offer of dialogue.
Breaking with the previous administration, U.S. President Barack Obama has said his administration is willing to engage with Iran, in a relationship strained most recently by Tehran's nuclear program.
Earlier in the day, Iran dismissed comments by the top U.S. military chief that it has enough fissile material to make a nuclear bomb.
Foreign Ministry spokesman Hassan Ghashghavi said Monday Tehran could not possibly further enrich the uranium it has without international inspectors being aware.
The International Atomic Energy Agency, which monitors Iranian production, says Iran has 1,010 kilograms of low-enriched uranium, which can be used for nuclear energy. A more complicated process is needed to further enrich uranium into weapons-grade material, and it remains unclear if Iran is capable of doing that.
IAEA chief Mohamed ElBaradei Monday urged Iran to unblock the stalemate in order to build confidence in its program.
On Sunday, the top U.S. military officer, Chairman of the Joint Chiefs of Staff Mike Mullen, said on CNN Iran has stockpiled enough material to make a nuclear bomb.
A Pentagon spokesman Monday clarified those remarks, noting that Mullen was asked about fissile material, which covers all forms of uranium. The spokesman said Mullen was referring to low-grade uranium.
The clarification followed remarks in a separate interview Sunday on NBC, by U.S. Defense Secretary Robert Gates, who said Iran is not close to having either a nuclear weapon, or a nuclear stockpile.
The United Nations nuclear agency said in a report last month that Iran had significantly increased its stockpile of low-enriched uranium since November. Some experts say Iran has enough of the material to convert into high-enriched uranium for one nuclear bomb.
Iran says its nuclear work is peaceful and aimed at generating electricity.
The IAEA began a week-long meeting of its board Monday. ElBaradei also said that "the apparent fresh approach by the international community" to talk to Iran also will help resolve the dispute. He did not mention the U.S. by name, but his remarks were widely seen as a reference to the administration of President Obama, who has said he is willing to open a dialogue with Tehran.
Asked about the possibility of a strategic relationship with Iran, Defense Secretary Gates said Sunday that is up to Tehran. He said he has been searching for "the elusive Iranian moderate" for 30 years, adding, he is still looking.
Some information for this report was provided by AP and Reuters.