"It [the house] was not a secret Iranian office," Barzani said.
"It is impossible for us to accept that an Iranian office in Irbil was doing things against coalition forces or against us. That office was doing its work in a normal way and had they been doing anything hostile we would have known that."
"They [the Americans] did not come to detain the people [the five Iranians] in that office."
Barzani suggested that the US forces had instead hoped to captured senior members of Iran's elite Revolutionary Guards who were visiting the area at the time.
"There was an Iranian delegation, including Revolutionary Guards commanders, and they came as guests of the president," Barzani said, refering to Jalal Talabani, the Iraqi president who is a Kurd.
"He was in Sulaimaniyah. They came to Sulaimaniyah and then I received a call from the president's office telling me that they wanted to meet me as well.
"They [the commanders] came here and they came openly. Their meetings with the president and myself were reported on television. The Americans came to detain this delegation, not the people in the office.
"They [Americans] came to the wrong place at the wrong time."
Washington has said the five captured Iranians, who were seized in Irbil, the capital of the Kurdish region, were seized on suspicion that they were providing aid to Shia fighters who are targeting US and Iraqi troops and civilians.
On Wednesday, a US military spokesman said that an delegation from the International Committee of the Red Cross had visited the captive Iranians.
On Friday, the US military issued a further statement clarifying that there were no Iranians in an Red Cross team that had visited the five detained Iranians.
The US has denied that it granted access to the Iranian captives as part of a deal which led to Iran freeing 15 British naval personnel who were seized by Iranian forces last month.