The ministry said in a statement that keeping diplomatic processes private best serves national interests.
Also on Sunday, government spokeswoman Fatemeh Mohajerani reiterated that "Iran's response to the sent letter was prepared and delivered."
Writing on social media platform X, Mohajerani added, "In this regard, the path of indirect negotiations with the United States is on the agenda, and the diplomatic process continues."
The confirmation follows reports from Iranian officials detailing Tehran's response to a recent letter from US President Donald Trump, which, according to Iranian sources, reiterated long-standing positions, rejecting key US demands regarding its nuclear and missile programs, as well as its regional alliances.
While the specifics of the exchanged letters remain confidential, in line with the Foreign Ministry's statement, Iranian officials have offered insights into Tehran's stance.
Foreign Minister Abbas Araghchi confirmed earlier in the week that Iran's official response to Trump's letter had been conveyed appropriately via Oman, a traditional mediator between the two adversaries.