MIAMI (AP) _ The U.S. arms deal with Iran has prolonged the war with Iraq, the Iraqi ambassador to the United States said today.

''Obviously this thing has led the Iranian government to believe its regional role is recognized by the United States,'' said Ambassador Nizar Hamdoon, ''even if it was at the expense of its neighbors and the expense of peace.''

He said the shipments have prolonged the war ''by at least months.''

The United States should return to its policy of cutting off arms supplies to the area to help bring peace to the region, said the ambassador.

Hamdoon made the comments during a news conference at Pan Aviation Inc., a company owned by the family of wealthy arms dealer Sarkis Soghanalian, a Lebanese who lives in Miami. The ambassador called Soghanalian ''a friend,'' and said he was not in Miami to make any arms deals for his country.

By building up Iran's role in the Middle East, Hamdoon said, the United States has encoraged ''more kidnappings of American people, more terrorism, more deaths on the war front.''

He said his country has not asked for any U.S. arms to balance the Iranian arms deal.

Asked if Iraq has received secret intelligence reports from the United States to aid its war effort, the ambassador said he was not at liberty to discuss bilateral contacts.