Talks to salvage the pact were in danger after a last-minute Russian demand forced world powers to pause negotiations for an undetermined time despite having a largely completed text.
Iran's Foreign Minister Hossein Amirabdollahian will visit Russia on Tuesday, Khatibzadeh said, without elaborating.
"We are currently having a breather from the nuclear talks," said Khatibzadeh.
"We are not at a point of announcing an agreement now since there are some important open issues that need to be decided upon by Washington."
Still, Iranian officials seemed cautiously optimistic in assessing the future of the negotiations, which have lasted 11 months.
"We will remain in the Vienna talks until our legal and logical demands are met and a strong agreement is reached," Ali Shamkhani, secretary of the Supreme National Security Council, which makes the decisions in the Vienna talks, said in a tweet.
Aside from the differences over the Vienna talks, tensions have also been rising since Iran attacked Iraq's northern city of Erbil on Sunday with a dozen ballistic missiles in an unprecedented assault on the capital of the autonomous Iraqi Kurdish region that appeared to target the United States and its allies.
Iranian state media said Iran's Revolutionary Guards Corps carried out the attack against Israeli "strategic centres" in Erbil, suggesting it was revenge for recent Israeli air strikes that killed Iranian military personnel in Syria.
Tehran had warned Iraqi authorities many times that its territory should not be used by third parties to conduct attacks against Iran, Khatibzadeh said.
"The central government of Iraq has the responsibility to ensure that its territory is not used as a base for attacks by third parties against Iran," said Khatibzadeh.
"Several times in the past, Iraq's territory was used against Iran by third parties including terrorist groups such as Kurdish militants, the United States and the Zionist entity," he added, referring to Israel.
In another setback for regional diplomacy, Iran said on Sunday it was suspending a fifth round of talks due this week in Baghdad with regional rival Saudi Arabia.
