The news came just a day after the UN Security Council unanimously adopted a new resolution again urging Iran to suspend its sensitive uranium enrichment work but offering no new sanctions and merely reaffirming existing ones.
ISNA quoted an unnamed official as saying that Aghazadeh would not be joining the September 29 to October 4 General Conference of the International Atomic Energy Agency in Vienna for "unknown reasons".
But it said his deputy Mohammad Saeedi and the country's ambassador to the IAEA, Ali Asghar Soltanieh, will represent Iran.
Iran and Syria, both under fire for allegedly engaging in clandestine nuclear activity, have been seeking a seat on the board of the UN atomic watchdog, much to the consternation of Western states.
The 35 members of the IAEA board are elected each year by the body's highest policy-making body, the General Conference, which comprises all 144 member states.
The IAEA has been investigating Iran's nuclear drive for the past five years, but has so far been able to determine whether its programme is entirely peaceful as Tehran claims.
The UN Security Council has slapped three rounds of sanctions on Iran over its refusal to come clean about its nuclear programme and its refusal to cede to international demands to cease uranium enrichment, a process which can be used to make the fissile material for a nuclear bomb.
Western powers accuse the Islamic republic of secretly trying to build an atomic bomb but Iran says its programme is designed purely to generate energy.
