Significant progress is being made in international talks on lifting sanctions on Iran in return for Tehran halting nuclear weapons development, according to the Minister for Foreign Affairs.
Simon Coveney was speaking following a meeting with the Iranian Foreign Minister in Dublin.
Ireland, as part of its role on the UN Security Council, is working restoring the Iran nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA).
The JCPOA, which was brokered in 2015, broke down following US withdrawal from the process in 2017 under then President Donald Trump.
Speaking to RTÉ after the meeting, Mr Coveney said: "I'm glad to say that progress is being made. There are negotiations as we speak in Vienna and I got a good update on the Iranian perspective on those negotiations.
"I think there is some optimism that we have and are continuing to make progress. A deal is far from done, because of course this is a technical negotiation in terms of clear commitments and reassurance and verification around those commitments.
"But we're in a much better space than we were a few months ago".
The EU and Russia today expressed optimism about progress in the talks, which are being held in Vienna.
In the US, President Joe Biden is facing calls from Republicans not to lift Trump-era sanctions on Tehran.
Mr Coveney said if the JCPOA was restored, it was expected Iran's role the Middle East and its backing of armed groups would be discussed.
However, he said all sides accepted such discussions were not part of the current talks.
"It’s not part of the conditionality, but it's part of the expectation in terms of where discussions will move to in the future... Let's get the JCPOA back functioning again.
"Let's then look at regional issues one by one, and I think that is an accepted approach now in Washington."
Fellow Fine Gael TD John Paul Phelan accused Minister Coveney of "cosying up" to Mr Zarif.
He said he was not comfortable with a photograph of the pair elbow bumping, saying they looked "like a couple of fellas having a cup of tea".
Deputy Phelan said there were significant human rights abuses in Iran and he wanted to know if issues such as executions, women and LGBT rights were discussed, as well as Tehran's funding of Hamas.
A department spokesperson said Mr Coveney and Mr Zarif had "a long and extremely detailed meeting" today, primarily in Ireland's capacity as facilitator of the Iranian nuclear deal on the UN Security Council.
He said several other topics were discussed, not least of all the horrific death and violence in the Middle East in recent days.
He added Ireland's call for a ceasefire and an end to hostilities, and for everyone in the region to support the same, was relayed very strongly.
US envoy optimistic on Iran nuclear talks
The EU official leading talks to revive Iran's nuclear deal said he was confident a deal would be reached as the negotiations adjourned, although European diplomats said success was not guaranteed, with very difficult issues remaining.
The talks resumed in Vienna on 7 May with the remaining parties to the deal - Iran, Russia, China, France, Britain and Germany - meeting in the basement of a luxury hotel, and the United States based in another hotel across the street.
Iran has refused to hold direct talks with the United States on how to resume compliance with the 2015 deal, which former President Donald Trump abandoned in 2018, prompting Tehran to begin violating its terms about a year later.
"I am quite sure that there will be a final agreement... I think we are on the right track and we will get an agreement," Enrique Mora, who is coordinating indirect talks between Iran and the United States, told reporters at the end of a fourth round of negotiations.
Russia's envoy, Mikhail Ulyanov, echoed those comments, saying on Twitter he hoped a final round expected to begin next week would be the last one.
The crux of the original agreement was that Iran committed to rein in its nuclear programme to make it harder to obtain the fissile material for a nuclear weapon in return for relief from US, EU and UN sanctions.
Senior diplomats from Britain, France and Germany (a grouping known as the E3) offered a note of caution, saying that while there was some tangible progress with the contours of a final deal emerging, success was not guaranteed.
"There are still some very difficult issues ahead. We do not underestimate the challenges that lay before us," they said in a statement.
Mr Mora said there was a common understanding on what was needed for a US to return to the deal, lifting of related sanctions and the resumption of nuclear commitments by Iran.
"It can be said now that the framework and structure of the agreement has been defined and many clauses of the agreement are being negotiated," Iran's top nuclear negotiator, Abbas Araqchi, told Iranian state TV.
Officials have said they want to move ahead before Iran's presidential election in mid-June, fearing the campaign could poison talks.
They have also had a soft deadline of 21 May, when an agreement between Tehran and the IAEA, the UN nuclear watchdog, on continued monitoring of some Iranian nuclear activities is due to expire.
The E3 diplomats said it was critical that Iran allow the IAEA to continue its necessary monitoring and verification work and urged Tehran and the agency to find a way forward.
"IAEA access will of course be essential to our efforts to restore the JCPOA, as a deal cannot be implemented without it," they said.
Additional reporting by Reuters