But EU foreign ministers stopped short of promising a resumption of talks on a lucrative trade deal as reward for Iran's promises to come clean on its nuclear drive.
In a statement, the ministers asked Solana "to visit Tehran early in 2004 to discuss the modalities of taking forward the EU's dialogue with Iran in all areas".
Diplomats said the Spanish official's visit would be in January but that dates have yet to be fixed.
The statement "reiterated the EU's readiness to explore ways to develop wider political and economic cooperation with Iran".
"This can only be achieved through full international confidence in Iran's adherence to non-proliferation and, in particular, in the peaceful nature of Iran's nuclear programme, as well as improvements in the areas of human rights, fight against terrorism, and Iran's position on the Middle East peace process."
Diplomats said the EU's Italian presidency, supported by Austria and Greece, had pushed for the statement to mention a resumption of talks on the trade and cooperation agreement, but this was omitted in the final version.
"It's far too early for the EU to hold out any prizes to Iran," one diplomat said.
The EU, which unlike the United States advocates a policy of constructive engagement with Iran, launched talks on the trade accord a year ago.
Four rounds of negotiations have been held but they were suspended in June over international concerns that Iran was secretly building nuclear bombs.
Iran helped to defuse the crisis by promising to comply with inspections by the UN's nuclear watchdog, the International Atomic Energy Agency (IAEA).
The IAEA last month condemned Iran for 18 years of covert nuclear activities but stopped short of bowing to US demands to haul Tehran in front of the UN Security Council for possible sanctions.
The EU statement said the bloc would review the situation after Solana reports back and after a report by IAEA chief Mohamed ElBaradei in February on the full scale of Iran's nuclear activities.