"Out of a steadfast commitment to salvage a deal that the US tried to torpedo, Iran has been the most active party in Vienna, proposing most drafts," Khatibzadeh said in a post on his Twitter account on Saturday.
The spokesman added that Iranians "Still believe a deal is possible if the US decides to abandon Trump's failed legacy."
Khatibzadeh's further warned Washington no to waste time and agree to lift all the sanctions against Tehran stressing, "Iran will not negotiate forever."
A recent research done by the Iranian parliament's Research Center (IPRC) found that the US is placing obstacles in the way of removing sanctions on the Islamic Republic as the Vienna talks between Iran and the P 4+1 were continuing, Mehr News Agency wrote.
Based on the JCPOA, Iran accepted curbs on its nuclear capabilities in return for the lifting of sanctions, but former US president Donald Trump unilaterally withdrew three years later and ramped up measures, prompting the Islamic Republic to pull back from its nuclear commitments in 2019 in retaliation.
Trump’s successor Joe Biden has signaled his readiness to return to the deal and state parties – also including Britain, China, France, Germany and Russia – have lately been negotiating its revival in Vienna with Iran.
Iran insists that all sanctions imposed by Trump need to be removed before the US reenters the deal, pointing to the promises of economic relief under the accord.
Iran on Friday said world powers must take any final decisions to revive the 2015 nuclear deal, after France and the US suggested that time was running out.
“The opposing sides are the ones who must take the decisions,” Iranian Foreign Ministry spokesman Saeed Khatibzadeh said in a statement.
The remarks came after French Foreign Minister Jean-Yves Le Drian and US Secretary of State Antony Blinken called on Tehran to take “difficult” decisions that could help advance negotiations to revive the accord, AFP reported.