"Some are condemning a plan before it's even had a chance to work," he said.
Iranian 'explosive devices'
Also on Friday, Bush authorised US forces in Iraq to take whatever actions necessary to counter Iranian agents deemed a threat to American troops or to the public at large.
"If Iraq is to succeed, it will need both groups to come to terms and to work together for the benefit of all Iraqis"
Iceman, Atlanta, US
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The aggressive new policy came in response to intelligence that Iran is supporting terrorists inside Iraq and is providing bombs - known as improvised explosive devices (IEDs) - and other equipment to anti-US fighters.
Gordon Johndroe, a National Security Council spokesman, said: "The president and his national security team over the last several months have continued to receive information that Iranians were supplying IED equipment and or training that was being used to harm American soldiers, "
While promising tougher action, the White House said the United States does not intend to cross the Iraq-Iran border to attack Iranians.
New Iraq commander
Meanwhile, the US Senate confirmed on Friday army general David Petraeus as the next commander of US forces in Iraq.
Confirmed on a vote of 81-0, Petraeus will be charged with implementing Bush's plan to send more US troops to Iraq in an effort to halt attacks and sectarian violence.
Petraeus, who will replace US army general George Casey, is just one of the new faces Bush is bringing to his team of top military and diplomatic officials in Iraq and the Middle East.
He has served two previous year-long tours in Iraq as commander of the 101st Airborne Division during the invasion in March 2003 and as commander of the training programme for the Iraqi army in 2004-05.