"There will not be a final deal before we agree on all topics," said Iranian Foreign Minister Mohammad Javad Zarif, who spoke to Iranian television.
"We will not accept any incomplete or ambiguous agreement," he emphasized.
Zarif added that Iran's nuclear program is "fully peaceful."
U.S. Secretary of State John Kerry said on Saturday that President Barack Obama is ready to stop the negotiations if he feels Iran does not show enough effort to prove that its program is peaceful.
Secretary Kerry underlined that his country may walk away from the nuclear talks with Iran, saying "there are still significant gaps" in the nuclear negotiations.
Abbas Araghchi, Iran's chief nuclear negotiator, said Friday that Iran is "pursuing changes in the procedures of the negotiations to accelerate the nuclear talks."
Sanctions on Iran
"There are still some disagreements about certain topics," said Zarif, adding "no specific agreement has been made yet" in the nuclear talks.
"Western countries, especially the U.S., and some political circles believe that sanctions on Iran are in their self-interest," the foreign minister said.
"However, the sanctions on Iran do not have any benefits for them, only costs," he explained, without elaborating on the "costs."
Zarif stated that it seems difficult to reach an agreement unless "negotiators change their mind and resist against political groups and individuals who benefit from the tension." He did not name the political entities he was referring to.
Iran's supreme leader, Ali Khamenei, vowed on Feb. 18 that his country will counter Western nations if they use sanctions as a weapon against the Iranian people. He also stressed that Iran could cut back its natural gas supplies to Europe.
P5+1 countries -- the U.S., Britain, France, Russia, China plus Germany -- and Iran reached an interim agreement on Nov. 2013 in Geneva, Switzerland, when Western sanctions on Iran were eased, and Iran stopped some of its uranium enrichment activities.
The negotiations were postponed for a second time after the group of P5+1 and Iran failed to meet the Nov. 24 deadline last year for a permanent settlement, as they now try to reach a final agreement before the final deadline on July 1.
According to Western members, Iran is secretly developing nuclear weapons in its uranium enrichment program, while Iran says that the program is for peaceful use of nuclear energy.