Iran said on Monday that the US position on Tehran's nuclear programme "has moved towards a more realistic one" ahead of a second round of talks.
"A cautious assessment is that, from the discussions that have taken place in Muscat to date, at least what we have been told is that the US position on the Iranian nuclear issue has moved towards a more realistic one," foreign ministry spokesman Esmaeil Baqaei said, according to the official IRNA news agency.
He added that Iran's "inalienable rights under the Non-Proliferation Treaty (NPT) were recognised", referring to the "peaceful uses of nuclear energy, including enrichment".
Tehran and Washington are due on Tuesday to hold a second round of negotiations - which began this month - after earlier talks collapsed during last year's Iran-Israel war.
Ahead of the latest talks, Baqaei said Iran would press for the lifting of long-standing US sanctions that have deepened the country's economic crisis.
"Time is of the essence for us. Our people are under the pressure of oppressive sanctions, and reason and logic demand that we lift these sanctions as soon as possible," he said.
Meanwhile, Israel has continued to violate its ceasefire in the Gaza Strip on Monday, killing at least one Palestinian in the Shujaiya neighbourhood, east of Gaza City.
Artillery shelling has also continued in areas under Israeli control, such as eastern Khan Younis and Deir al-Balah.
Israeli forces also opened fire at the al-Bureij camp, according to eyewitnesses.