Zakharova said the fate of the Iran deal would be decoded at a new meeting of the Joint Commission monitoring the implementation of the agreement in Vienna on May 25, which will not include the U.S. for the first time.
Iran expected this package by the end of May, he said, adding the country had only "a few weeks" before having to decide whether to keep participating in the deal or not. "I'm sorry to say that we haven't seen Plan B yet. The Plan B has just started to be figured out".
US President Donald Trump has long trashed the deal with Iran - concluded under his predecessor Barack Obama - saying it did not do enough to curtail Tehran's nuclear ambitions.
Also in exchange for Iran continuing to honor the deal, Khamenei said the European nations should guarantee that they will not only continue to buy Iranian oil but will try to block USA plans to curb Iranian oil sales through renewed sanctions.
In his meeting with Pompeo, Maas said he stressed the "great solidarity" of the deal's European signatories and the European Union in their collective decision to continue following the agreement.
He also said it did not go far enough in restricting Iran's ballistic missile program, or its intervention in regional conflicts from Yemen to Iraq and Syria.
Iran has struggled to benefit from the accord so far, partly because of remaining unilateral U.S. sanctions that have deterred major Western investors from doing business with Tehran.
Classified collusion briefing features top lawmakers, Federal Bureau of Investigation … and Trump's lawyer
House Speaker Paul Ryan (R-Wis.), who attended the first Republican-only briefing, also declined to discuss what he learned. Trump is already claiming that the tables have been turned on the Mueller investigation and the deep state.
The supreme leader called on nations to "guarantee the total sales of Iran's oil", which means the continent will have to make up for any oil sales which have been cancelled because of U.S. sanctions.
"If the USA succeeds in disturbing Iranian oil sales, the Europeans must promise to buy whatever quantity we wish to sell".
Mr Pompeo said the U.S. would inflict the "strongest sanctions in history" on Iran unless it agreed to 12 American demands, including withdrawing from Syria and halting its funding of militant groups like Hizbollah and Hamas.
"There's going to be a lot of discussions about SWIFT", Ellie Geranmayeh, a senior fellow at the European Council on Foreign Relations, told Bloomberg on Friday. U.S. Secretary of State Mike Pompeo on Monday threatened Iran with "the strongest sanctions in history" if it did not change its behaviour in the Middle East.
In all, Khamenei's statement laid down seven conditions for Iran to continue adhering to the nuclear deal. Some Western companies have already quit Iran or said they may have to leave because of the new United States sanctions.
The U.N. atomic watchdog policing the pact said on Thursday Iran continued to comply with the terms of the deal, but could be faster and more proactive in allowing snap inspections.
The official said that if they were unhappy with how things panned out they would seek a ministerial meeting and then decide.
French President Emmanuel Macron wants to complement the nuclear deal with negotiations among all sides over other issues, an idea cautiously received by Russian President Vladimir Putin during talks in St. Petersburg on Thursday. Its chief, Yukiya Amano, briefed participants before Friday's meeting.