"Now is an opportune moment to reach a genuine diplomatic solution that peacefully ends Iran's military nuclear program," he said. "This opportunity can only be realized if the international community continues to place pressure on Iran, because it is that pressure that has brought Iran back to the negotiations in the first place."
Not everyone is pleased with the talks.
Alireza Jafarzadeh, with the opposition National Council of Resistance of Iran, accused Iran of using them to buy time to move forward with its nuclear weapons program. He called for still tighter sanctions.
"The P5+1 is allowing Iran to talk its way into a nuclear bomb; this explains the new atmospherics and smiles by the Iranian regime's officials," Jafarzadeh said. "The ruling mullahs only understand the language of strength and decisiveness. More concessions will only result in more deceit by the Iranian regime."
Ali Larijani, Iran's powerful parliamentary speaker and a close associate of the nation's supreme leader, Ayatollah Ali Khamenei, said last week that Iran is serious about resolving the dispute over its nuclear program.
It is keen to resolve the issue "in a short period of time," he told CNN's Christiane Amanpour in an exclusive interview from Geneva. "From Iran's side, I can say that we are ready," he said.