Iran is still reviewing the final text of a possible deal with the US and no response has yet been sent, Iran's semi-official news agency Mehr reported, citing a source familiar with the matter.
Iran is seeking to achieve "real, tangible" benefits, the source added, saying that "the history of US non-compliance and historical distrust" has led Tehran to view the issue "very strictly."
Tensions in the Middle East have escalated since the US and Israel launched strikes on Iran in February. Tehran retaliated with attacks targeting Israel and US allies in the Gulf, alongside the closure of the Strait of Hormuz.
A ceasefire took effect on April 8 through Pakistani mediation, but subsequent talks in Islamabad failed to produce a lasting agreement. Efforts for a solution, however, have continued since.
One of Iran's conditions to end the war permanently is the end of fighting on all fronts, including in Lebanon, where the latest Israeli assault continues since early March.
US President Donald Trump on Monday said he asked Israeli Prime Minister Benjamin Netanyahu to pull back his troops from Beirut.
