Iran will not negotiate with the United States until it stops its "evil approach", the government spokesman was quoted as saying on Tuesday, two days before the two foes were due to attend a meeting on Iraq.
U.S. officials say Secretary of State Condoleezza Rice is ready to talk with Iran on the sidelines of the May 3-4 conference in Egypt, if such contact is deemed useful.
But Iran appeared to dismiss the possibility of bilateral discussions at the meeting in the Red Sea resort of Sharm el-Sheikh, which is to seek ways to end the violence in Iraq and will be attended by major powers and Baghdad's neighbors.
Iran and the United States have not had diplomatic ties for nearly three decades and are sharply at odds over the conflict in Iraq and Tehran's nuclear ambitions.
Asked if Rice and Iranian Foreign Minister Manouchehr Mottaki may hold talks in Egypt, his deputy Mahdi Mostafavi said according to the ISNA news agency:
"No, so far the necessary situation for talks and negotiations is not ready."
Washington accuses Iran of destabilizing Iraq and U.S. officials say Rice would probably limit any discussions to this.
Iran denies meddling in Iraq and blames the U.S.-led invasion in 2003 for violence that is threatening to tear Iraq apart, saying U.S. forces should leave the country.
Tehran: Iran a power to be reckoned with
Government spokesman Gholamhossein Elham suggested Washington wanted to talk to Tehran because of its problems in Iraq and a realization Iran was a growing regional power.
"The Americans know that they are faced with Iran as a real, capable power because Iran has entered the field of the nuclear technology and has the will to move forward," ISNA quoted him as saying.
"That is why they are after negotiating with Iran somehow," Elham said. "Naturally until the Americans stop their arrogant, one-sided and evil approach we won't negotiate with them."
Washington cut ties with Tehran in 1980, after the Iranian Islamic revolution and the holding of U.S. hostages, and has spearheaded a drive to isolate Iran over its nuclear program.
It has made clear it will only engage in broader talks when Iran halts sensitive uranium enrichment, which can be used to fuel power stations or make atomic weapons. Iran denies Western accusations it is seeking to develop nuclear bombs.
But the U.S. State Department has said Rice is open to direct talks with Iran over Iraq. Iraq's foreign minister said on Sunday there was a "high possibility" Iran and the United States would hold bilateral discussions at the Egypt meeting.
Elham said Iran would be ready to negotiate with the United States if it changes its behavior and is no longer a "terrorist and evil government" but made clear his view that Washington was more keen for such talks than Tehran was.
"About negotiations, it is Miss Rice who really would like to have a friendly chat with Mr. Mottaki," he said.