The United States and Iran have been conducting negotiations over the past month on a deal to curb Iran's nuclear program in return for the lifting of financial sanctions.
New dates would be announced when mutually agreed, Omani Foreign Minister Badr Albusaidi said in a post on X.
Albusaidi, who has mediated the talks through three rounds so far, did not elaborate.
US negotiators said the United States "had never confirmed its participation" in a fourth round of talks in Rome.
However, the person said the US expected the talks to occur "in the near future".
The person spoke on condition of anonymity to discuss the closed-door negotiations.
Two other rounds of talks have been held in Muscat, the capital of Oman.
A new date will be set "depending on the US approach," a senior Iranian official told Reuters on Thursday.
"US sanctions on Iran during the nuclear talks are not helping the sides to resolve the nuclear dispute through diplomacy," the official said.
"Depending on the US approach, the date of the next round of talks will be announced".
Earlier, Iran accused the US of "contradictory behaviour and provocative statements" after the US warned Iran of consequences for backing Yemen's Houthis and imposed new oil-related sanctions on it in the midst of nuclear talks.
Separately, a foreign ministry spokesperson in Tehran said Iran will continue to engage "seriously and resolutely" in result-oriented negotiations with the US, state media reported.
On Wednesday the US imposed sanctions on entities it accused of involvement in the illicit trade of Iranian oil and petrochemicals.
Separately, US Defense Secretary Pete Hegseth warned Iran that it would face consequences for supporting the Houthis, who control northern Yemen and have attacked ships in the Red Sea in what the group says is solidarity with the Palestinians.
with AP
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