AA nuclear negotiator highlighted the benefits Iran has derived from the 2015 nuclear agreement with major powers, formally referred to as the Joint Comprehensive Plan of Action.
"No domestic institution can claim that it faces an obstacle because of JCPOA. The action plan has fulfilled its task," Abbas Araqchi also told a press conference in Tehran on Sunday, a day ahead of the one-year anniversary of the deal's implementation.
Under the accord, Iran agreed to curb its nuclear work in exchange for relief from international sanctions that targeted its key economic sectors, including oil, banking and transport.
"It can be justifiably claimed that oil, gas and energy sectors have normalized. The level of oil sales is acceptable and oil revenues are completely accessible," Araqchi was quoted as saying by IRNA.
Since the pact went into force, Iran has made efforts to recoup oil market share it lost after the introduction of international sanctions on its oil sector in 2012.
It has to date reached at least 80% of its pre-sanctions oil output, Iranian officials have said.
Araqchi said despite the remaining US restrictions, Iran's banking system is in "good" condition.
"The banking situation has not returned to normal after JCPOA, but this has little to do with JCPOA. The main culprit is the US non-nuclear sanctions … All in all, our banking and financial conditions are good."
These US restrictions include a ban on the use of Washington's financial system to process dollar-based transactions linked to Iranians.
Overseas banks and firms back away from Iran's market on fears they could incur considerable losses in punishment for violating the vague US sanctions, even though unwittingly.
Experts partly blame Iran's complex regulations, a lack of transparency in its banking system, unclear dispute resolution mechanisms and labor issues for the behavior of foreign businesses.
Araqchi said the Islamic Republic will never agree to a demand by the incoming US administration to revise the nuclear accord.
"Nuclear negotiations with the United States are over and we will not reengage in negotiations [over the deal] with the current or the next US administration. For us, JCPOA is a closed issue," he said.
He was responding to a recent call for the revision of the action plan by Rex Tillerson, a candidate for the post of secretary of state under US president-elect, Donald Trump, who will take office next week.
Trump railed against the accord as he campaigned for the White House, calling it "a disaster" and "the worst deal ever negotiated".
Tillerson echoed that position during a hearing of the US Senate Foreign Relations Committee on Wednesday, pledging a "full review" of the pact if he got the top diplomat's post.
He said he would increase monitoring and verification systems to ensure Iran does not violate the nuclear agreement.
"We need ... to examine our ability to clarify whether Iran is complying," Tillerson told the committee. "That means no nuclear enrichment in Iran, no storing of nuclear materials in Iran."