The talks come as many in Iran are anxious about a possible return to all-out war.
Israeli and American leaders have been sharpening their threats ahead of elections in both countries, while Iranian leaders have remained defiant.
Saudi Defence Minister Khalid bin Salman, Pakistani army chief Field Marshal Asim Munir and Ibrahim Kalin, the head of Turkey's intelligence service, were to meet Iran's top security officials and negotiators on Monday to push for a deal between Tehran and Washington.
The war in Yemen and strikes by Iranian-backed Houthi rebels against Saudi Arabia were also topics of the talks, according to two regional officials who spoke on condition of anonymity because they were not authorised to speak to reporters.
Iranian foreign ministry spokesman Esmail Baghaei told reporters the agenda for the meeting was not set, but the talks would "undoubtedly address the most pressing threats to regional security".
Saudi Arabia said the delegations hoped to find "ways to de-escalate tensions, enhance regional security and promote its stability".
Qatari mediators also travelled to Tehran on Sunday, working in co-ordination with the US, as part of efforts to de-escalate regional tensions.
Pakistan and Qatar helped broker an agreement in June aimed at having Iran fully reopen the Strait of Hormuz to shipping, ending a US blockade of Iranian ports and opening negotiations on a broader settlement addressing Iran's nuclear program.
The deal unravelled quickly, however, as both sides renewed attacks.
With worries about renewed fighting before Israel's election on Tuesday and the November 3 midterm elections in the US, Baghaei at the weekend said Tehran had not closed the window of diplomacy and that messages were being passed to the US via intermediaries.
With negotiations long stalled, he said the US appears to be persisting in unilateral demands and that President Donald Trump and US officials repeatedly use the phrase "complete surrender", which Baghaei said no Iranian accepted.
Israeli Prime Minister Benjamin Netanyahu, meantime, repeated his warning on Sunday that Iran or its proxies could attack before the close elections to disrupt the vote, citing intelligence.
"The (military) is ready both to defend and to strike," he said in a video statement, adding: "You will suffer disproportionate blows far greater than you can imagine."
Israel's Channel 12 reported on Sunday that Netanyahu and his military chief of staff clashed over an instruction by Netanyahu to carry out an "action" that the army believed could quickly trigger a resumption of the conflict with Iran.
Netanyahu's office later described the report as "fake news".
In Tehran, when asked whether Iran was planning attacks, Baghaei said only that "the Israeli regime is highly skilled at carrying out false-flag operations", and Iran would not hesitate to exercise its right to self-defence.
Yemen has become a widening front in the Iran war that began in February, with the Houthis increasingly launching attacks on Saudi Arabia because it supports Yemen's internationally recognised government battling the rebels.
The conflict has intensified since forces from the internationally recognised government and Saudi-led coalition launched air strikes on Houthi-held Sanaa International Airport in July, shattering a 2022 ceasefire deal that largely stopped the fighting in the country's civil war.
Early on Monday, Houthi military spokesman Yahya Saree said the rebel group had fired ballistic missiles at military gatherings and weapons depots belonging to Saudi-backed government forces in Aden and Lahj provinces.
He claimed the attacks destroyed military equipment and caused casualties but did not provide evidence.
The spokesperson for the Saudi-led coalition said an operation in Houthi-controlled territory destroyed five tunnels used for storing ballistic missiles, four ballistic missile launchers and another missile storage.
