According to Iranian officials, the EU had warned that Iran must co-operate fully with the United Nation's nuclear watchdog agency or risk trade restrictions.
Foreign Ministry spokesman Hamid Reza Assefi said it was unacceptable to impose conditions attached to talks with the EU.
On Monday EU foreign ministers expressed “increasing concern” over Tehran’s nuclear programme.
In a joint statement the 15-member bloc said they expected Iran to “show full transparency and co-operate fully with the IAEA”, in reference to the International Atomic Energy Agency.
“We believe continuing these negotiations in a climate of trust, without conditions and on an equal basis in beneficial and possible,” said Assefi.
Iran continues to be committed to the Nuclear Non-Proliferation Treaty (NPT) and fully co-operates with the IAEA, said Assefi.
The EU foreign ministers said they would review future steps of co-operation with Iran in September, adding their next moves depend on a report by IAEA director Mohammad al-Baradei.
Kharzai (L) said Tehran would
consider surprise searches
Iran has come under mounting pressure, particularly from the United States, for its nuclear plant. Tehran says it generates electricity while Washington accuses the Islamic Republic of working towards nuclear arms.
Less than 24 hours after the joint EU statement, Iran said it was considering whether to allow surprise inspections of its nuclear sites.
Tehran will decide on whether or not to sign the NPT protocol after hearing legal experts from the IAEA it has invited to visit Tehran, said Foreign Minister Kamal Kharzai.
The Foreign Minister was speaking at a press conference during a visit to Pretoria, South Africa.
Kharzai said there should be no concern from the European foreign ministers, stressing Tehran is co-operating with the nuclear watchdog.