The announcement comes a day after Washington said Iran had agreed to ease key demands that had held up the revival of the 2015 deal trashed by former president Donald Trump.
That came one day after Tehran criticised the United States for what it said was a slow response to its proposals.
Tehran "received this evening via the (EU) coordinator, the response from the US government over the Islamic republic of Iran's opinions on the outstanding issues in the negotiations to lift sanctions", Iranian foreign ministry spokesman Nasser Kanani said.
"The process of carefully reviewing the US opinions has begun and the Islamic republic of Iran will announce its opinion in this context to the coordinator after it completes its review," Kanani added, without providing further details.
Iran had last week sent its proposals over the final draft sent on August 8 by the EU, which has coordinated talks in Vienna on reviving the pact.
Shortly after Tehran's announcement, Washington confirmed it had responded to Iran's proposals.
"As you know, we received Iran's comments on the EU's proposed final text through the EU," State Department spokesman Ned Price said.
"Our review of those comments has now concluded. We have responded to the EU today".
The 2015 agreement between Iran and six world powers -- Britain, China, France, Germany, Russia and the United States -- gave the Islamic republic sanctions relief in exchange for curbs on its nuclear programme.
The deal formally known as the Joint Comprehensive Plan of Action, or JCPOA, was designed to prevent Iran from developing a nuclear weapon -- something it has always denied wanting to do.
Iran's announcement comes as its arch-nemesis Israel has piled on pressure on Western countries to halt talks on reviving the agreement, warning against the consequences of returning to the accord.
"On the table right now is a bad deal. It would give Iran $100 billion a year," Israeli Prime Minister Yair Lapid told journalists Wednesday.
The money would be used by Iran-backed militant groups Hamas, Hezbollah and Islamic Jihad to "undermine stability in the Middle East and spread terror around the globe," he added.
