Speaking at a conference in Rome, Araqchi said he believed it was possible for Iran to reach an accord with world powers in time for a July 20 deadline, with drafting of final proposals due to begin next week.
"We need hard work and wisdom and logic to overcome disagreements," Iran's Fars news agency quoted him as saying.
"Iran will return to 20 percent enrichment if a deal cannot be reached ... failure to reach a deal will be a disaster for everyone," he was quoted as saying.