Asked on Monday if he had ever considered resigning, Powell flatly replied, "No."
"I explained to my colleagues on the national security council and to the president the ups and the downs, the ins and the outs, of this kind of an operation. But I was always supportive of what we were trying to do," he said.
Pundits have questioned whether Powell should have stepped down after a new book by journalist Bob Woodward depicted him as raising questions about the difficulty of occupying Iraq.
"You are going to be the proud owner of 25 million people," Woodward quoted Powell as telling US President George Bush. "You will own all their hopes, aspirations and problems. You'll own it all."
The United States is now facing an accelerating insurgency in Iraq, with resistance fighters in the town of Falluja and Najaf.
Political analysts doubt Powell will remain in Bush's cabinet if he wins the upcoming election in November
Powell told Reuters people had misinterpreted his desire to raise all issues involved before invading Iraq as opposition to the decision to invade, which he said he supported.
"I would always have loved to see a peaceful diplomatic solution to problems, that's what diplomats are supposed to do and secretaries of states and most sensible generals."
US Secretary of State
He said he had helped persuade Bush to go to the United Nations to seek a diplomatic solution that might have persuaded Iraqi President Saddam Hussein to give up the weapons of mass destruction that Washington believed he had.
US search teams have not found any stockpiles of such weapons, which formed Bush's central justification for the war.
"A diplomatic solution was there but eventually the president concluded, we all concluded, that it wasn't going to work, there wasn't time for this to work ... and the president made a decision that military action was appropriate," he said.
"I knew that was a decision that he might have to make if the diplomatic solution didn't work. He made that decision in March. And I knew that when that decision came we would go to war. So there is no conflict in my mind," he said.
"There is no basis for me to consider whether or not I had done my job or I should move on. We wanted to get rid of that regime. That regime is gone. I am pleased that Saddam Hussein is gone," Powell said.
Powell added: "I would always have loved to see a peaceful diplomatic solution to problems, that's what diplomats are supposed to do and secretaries of states and most sensible generals."