"Most of our disagreements have been resolved, but we have not reached a final solution yet. I think it is unlikely that we will reach a result with Europe by today or tomorrow," Rouhani told a Cabinet meeting in Tehran, two days ahead of a deadline set by Iran for Europe to save the 2015 nuclear accord, his website reported.
Since the United States pulled out of the UN-endorsed agreement last year, the European parties to the pact have been trying to convince Iran to remain compliant by promising to shield its economic interests from reimposed and toughened US sanctions.
Iran has vowed to keep reducing its commitments every 60 days unless Europe upholds its side of the deal and offsets the impact of US exit, according to Financial Tribune.
In the first two phases, it surpassed the limits set on the size of its stockpiles of enriched uranium and heavy water, and exceeded the maximum uranium enrichment level it had agreed to.
Third Step
Rouhani said Tehran's recent negotiations with the European signatories were a "step forward" and the Iranian and European views have become closer, but "we will take the third step".
He said the details of Iran's next moves to scale back its nuclear commitments, which will have a significant impact, will be announced in due course.
Iranian officials had previously said their plans could include enriching to 20% or restarting mothballed centrifuges, machines that enrich uranium.
"The third step would not seem very dramatic, but it is extremely important in nature. I think it will be the most important step taken so far and have extraordinary effects."
The president said Europeans will have another two months to find a final solution.
"We will continue negotiations to reach an agreement while taking the third step. The door of dialogue and logic will always remain open," he said.
Mutual Understanding
Referring to ongoing talks with Britain, France and Germany, Rouhani said, "We now understand each other very well. They know what we want and we know what they want. Everything is clear."
He said a five-month framework has been defined for talks with France, which is coordinating the next steps in consultation with the remaining participants, including the United States.
French President Emmanuel Macron has spent the summer trying to create conditions that would bring the sides back to the negotiating table.
According to western and Iranian sources quoted by Reuters, Paris has proposed to offer Iran about $15 billion in credit lines until the yearend if Tehran comes back into full compliance with the nuclear pact, a move that hinges on Washington not blocking it.
Rouhani said American hardliners, Israel and some Arab governments in the region do not want to see a "fair" relationship between Tehran and Washington, and keep taking measures that undermine efforts to end the standoff.