Pakistan's military chief, Field Marshal Asim Munir, has landed in Tehran for talks amid renewed risk of escalation in the Gulf, the state news agency IRNA reports.
Fears of a renewed outbreak of war by the United States and Israel against Iran have risen again in recent weeks.
Munir has previously mediated between the Iranian leadership and the US.
On Monday, US Defense Secretary Pete Hegseth made a surprise trip to Israel, meeting Prime Minister Benjamin Netanyahu at an air force base in the south of the country.
The media reported that Iran has held military exercises and missile tests in recent weeks.
Russian Foreign Minister Sergei Lavrov was also in Tehran for talks on Monday.
"Never in our history have Iran and Russia worked as closely as now," his Iranian counterpart Abbas Araqchi wrote on X after the meeting.
Iran is also hoping for military support from Russia in its conflict with the US.
The visits by Lavrov and Munir should be considered the start of a Russian de-escalation initiative for the region, Pakistani intelligence sources told the DPA news agency.
The talks concern both a possible agreement between the US and Iran, and the conflict in Yemen between the Iran-aligned Houthi militia and Saudi Arabia.
As an ally of Saudi Arabia, the Pakistani negotiator is to convey a message to the government in Iran.
"Munir will tell them that the Houthis' aggression could also drag Pakistan into a conflict with Iran," an intelligence officer told the DPA news agency.