Iran says the issue of suspending its uranium enrichment program is not negotiable.
A government spokesman made those remarks Saturday, in response to a recent report by the International Atomic Energy Agency (IAEA) that is critical of Iran's nuclear program.
The report said Tehran has not provided enough evidence to refute Western accusations it is trying to make atomic weapons.
EU foreign policy chief Javier Solana is expected to visit Iran soon to deliver a new package of incentives aimed at persuading Iran to stop enriching uranium.
The package was drafted by Germany and the five permanent members of the U.N. Security Council - the U.S., Britain, France, Russia and China.
The council has passed three sets of sanctions on Iran for its refusal to stop enriching uranium, a process that can be used to make nuclear weapons.
The United States and its Western allies accuse Iran of working to produce nuclear weapons. Iran says its atomic program is peaceful.
Some information for this report was provided by AFP, AP and Reuters.