Iran's official IRNA news agency quotes Foreign Ministry spokesman Mohammad Ali Hosseini as saying that "talks with the U.S. [are] not on Iran's agenda."
The comments came one day after Iraq announced that ministers from Iraq's neighboring countries, the five permanent members of the UN Security Council, and industrialized states will meet in Egypt in early May to discuss the situation in Iraq.
U.S. and Iranian ambassadors gathered at a closely watched security conference in Baghdad's Green Zone on March 10.
Iranian officials expressed hope after that meeting that it might be a "prologue" to ministry-level discussions.
Washington has accused Iranians of helping to fund Iraqi militias and with providing them with military expertise and technology.
The United States cut off all official diplomatic ties with Iran following the storming of the U.S. Embassy in Tehran and the capture of U.S. hostages after Iran's Islamic Revolution in 1979.
Washington has also pressed the international community to take steps to curb what it alleges is an Iranian effort to develop and possess nuclear weapons -- a charge Tehran rejects.