Two Pakistani government sources also confirmed the visit to Reuters, with one saying Pakistan and Iran were in direct contact over the ongoing regional crisis.
Pakistan has taken on a mediating role between Iran and the United States as both sides seek to end the conflict that began after US and Israeli strikes on Iran in February.
The Shehbaz Sharif government previously brokered a two-week ceasefire between Tehran and Washington on April 8, ending six weeks of fighting. Islamabad has since continued to relay messages between the two countries.
According to a Pakistani government source, Munir's talks in Tehran will cover efforts to advance peace under Islamabad's memorandum of understanding, US President Donald Trump's warnings of tougher sanctions against Iran, and regional developments following the Pakistan-Turkiye-Saudi Arabia defence agreement.
The source said the situation involving the Iran-aligned Houthis would also be discussed.
Munir's visit comes amid rising tensions over Trump's plans to impose further sanctions on Iran. US officials have described the planned measures as potentially the "toughest sanctions in history".
Trump has also warned countries against providing Iran with "any type of lifeline" as Washington seeks to increase pressure on Tehran.
Meanwhile, tensions remain high around the Strait of Hormuz, where oil shipments have been severely disrupted. Iran has threatened military action against unauthorised oil tankers attempting to use the vital waterway.
Pakistan has stepped up its diplomatic engagement in recent months. Interior Minister Mohsin Naqvi visited Tehran in August, where he held talks with Iranian President Masoud Pezeshkian and Foreign Minister Abbas Araghchi.
The first round of direct US-Iran negotiations was held in Islamabad on April 11 and 12 following the Pakistan-brokered ceasefire. Although the talks ended without an agreement, diplomatic efforts have continued.
