European Union foreign policy chief Javier Solana, who jetted in to Tehran to present the proposal on Tuesday, said he is "more optimistic today than a month ago" -- when Iran was ruling out any talk of halting sensitive nuclear work.
"On the nuclear question, we prefer cooperation to confrontation," the official IRNA news agency quoted Foreign Minister Manouchehr Mottaki as saying.
"The proposals were submitted by Mr Solana and we are going to carefully study them," said Mr Mottaki.
"Shuttle diplomacy, if it is in good faith, would allow us to find grounds for understanding."
The package -- which offers trade, diplomatic and technology incentives in return for a freeze of enrichment -- was drawn up by Britain, France and Germany and is backed by the United States, Russia and China.
It is aimed at resolving fears that Iran could acquire nuclear weapons yet at the same time seeks to guarantee the country's access to atomic energy.
Top national security official Ali Larijani has said it contained "positive steps" but also "ambiguities" -- signalling no immediate decision from Tehran is likely.
"I don't say that everything has been resolved but I'm more optimistic today than a month ago," Mr Solana told reporters in Potsdam, eastern Germany.
"I hope they will call me back soon and give an answer to the proposal," he said, adding that he is prepared to go back to Tehran if necessary.
While being offered incentives, Iran also faces the stick of robust UN Security Council action, including a range of possible sanctions, if it rejects the offer.
Russia, however, still appears to be against the use of sanctions in the dispute.
"Any measures that could be supported by Russia in the Security Council can only be in situations when Iran starts to act in contradiction to its obligations under the nuclear Non-Proliferation Treaty," Foreign Minister Sergei Lavrov was quoted as saying by the RIA Novosti news agency.
Currently "there is no discussion of sanctions against Iran in the Security Council," Mr Lavrov told Russia's lower house of parliament.
The deadline for Iran to decide is said to be before the G8 meeting of foreign ministers in Russia next month, according to a Western diplomat who asked not to be named.