The visit by Steve Witkoff, US President Donald Trump's special Mideast envoy, and Jared Kushner, his son-in-law, comes after a weekend of crossfire in the region over efforts to reopen the Strait of Hormuz to shipping traffic.
The envoys will not be having direct negotiations with Iranian diplomats while in Qatar's capital Doha, Qatari foreign ministry spokesman Majed al-Ansari said.
Instead, mediators are working for the time being as go-betweens for the talks, which will not include any high-level officials, he added.
The technical talks this week on issues including regional security could later be elevated to senior level, he said.
Iran is also sending a delegation to Qatar this week.
Iran's foreign ministry spokesman Esmail Baghaei said on Tuesday that Iran has had no plans for a meeting with the US side at any level in the coming days.
"What will take place in Doha tomorrow is a discussion with the Qatari side about implementing parts of the memorandum of understanding, including the release of Iran's blocked assets," Baghaei told reporters at his own briefing.
It is possible the two sides could exchange messages through the Qatari mediators.
The White House had said on Monday that Kushner and Witkoff would hold "high-level meetings," with technical discussions to continue on the sidelines.
The US and Iran agreed to an interim deal earlier this month that calls for Iran to dilute its stockpile of enriched uranium.
It also waives US-backed oil sanctions on the country, calls for free traffic through the Strait of Hormuz and gives each side 60 days to hammer out broader agreements.
Iranian President Masoud Pezeshkian said on Monday that Qatar plans to release $US6 billion ($A8.7 billion) in frozen Iranian assets.
A US official, speaking on condition of anonymity because of the sensitive negotiations, confirmed the release amount, saying it would be used to buy US food products for the Iranian people.
A fifth of the world's oil was shipped through the Strait of Hormuz before the war began.
The strait has long been considered an international waterway despite being in Iran and Oman's territorial waters.
Both sides traded strikes amid efforts last week to open Oman's territorial waters in the strait to both inbound and outbound ship traffic from the Persian Gulf.
That raised concerns that negotiations to formally end the war could be disrupted.
Since last Thursday, the US has accused Iran of hitting at least two commercial ships with missiles or drones, and it bombed Iranian military facilities in response.
Iran in turn launched missiles and drones at US military sites in Kuwait and Bahrain on Sunday, with both sides accusing each other of breaking the ceasefire.
"The meeting in Doha is going to be perhaps important, perhaps not," US President Donald Trump told reporters in the Oval Office.
"We're going to find out."
with Reuters
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