The US has accused Iran of backing Shia militia groups in Iraq and seeking an atomic bomb.
Iran denies both accusations.
Mottaki said: "We are facing two problems in Iraq, one relates to instability caused by terrorist activities and the other by continuation of occupation of Iraq.
"We believe that the correct approach to the issue is to look into both areas of difficulties."
The confirmation of the date for the talks comes days after Iranian officials said that the rare talks would be held within the next few weeks, most likely in Baghdad.
Ayatollah Ali Khamenei, Iran's supreme leader, on Wednesday dashed any expectations that the meeting would produce a breakthrough, saying its policy of not negotiating with the US was unchanged.
He said Iran would merely use the talks with US diplomats over Iraq to remind Washington of its "occupiers' duty" in the conflict-torn country.
Hoshiyar Zebari, the Iraqi foreign minister, has welcomed the talks, saying both the US and Iran were major players in his country.
"Let the people of Iraq vote if they want the US to stay or leave"
Bob Kaye, Bohemia, US
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US officials have often said they would meet with Iranian counterparts but that talks would have to be limited to Iraq.
With violence escalating in Iraq, and George Bush, the US president, under increasing domestic pressure to wrap up the four-year-old war, many experts say Tehran could play a major role in stabilising Iraq.
Recently, Bush selected a general as his "war tsar" to oversee the fighting in Iraq and Afghanistan.
The White House tried for weeks to fill the position and approached several candidates who reportedly turned it down, before Lieutenant-General Douglas Lute, the defence department's director of operations, agreed to take the job.