Mohammad Javad Zarif said the decision to restart negotiations and seek a deal over the Islamic republic's disputed nuclear programme had reduced tension and would not be reversed.
But Zarif, who has led the Iranian side in talks with world powers that last month saw an interim agreement extended to June 30 next year, denied his team was bargaining "like carpet sellers" for a better deal.
"Because of these negotiations the Islamic republic of Iran has become safer... And less vulnerable than before," he told students in Tehran in a speech carried live on state television.
Israel and the United States have said all options, including military measures, remain on the table should Iran not rein in its nuclear programme.
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At the most recent negotiations, Iran and the P5+1 group (Britain, China, France, Russia and the United States plus Germany) missed a November 24 deadline for a comprehensive agreement.
But they agreed to keep talking and set new deadlines of March 1 for a broad political framework and June 30 for the fine print of the final deal.
Respect for Iran has increased since talks officially restarted in 2013, Zarif said, but the process has been hampered by "the Westerners having a wrong concept of how Iranian officials negotiate".
"They used to believe that Iranians 'taarof', kill time, bargain like carpet sellers and give concessions at the last minute," he said.
"This wrong conception of our behaviour has caused us not to be able to reach our objectives in negotiations," he added, with more time needed for coming to terms on "details".
President Hassan Rouhani, meanwhile, echoed Zarif's comments on the nuclear talks and said the real challenge was to improve Iran's economy after years of sanctions.