Asked whether it was a failure for the summit that four large countries had not completely lifted restrictions on their troops, known as caveats, Prodi said: "No, it's a clear position and it was an obvious position."
The most urgent needs are in southern Afghanistan, the main battleground with resurgent Taliban fighters, where Canadian, British and Dutch soldiers have suffered heavy casualties.
"To succeed in Afghanistan, Nato allies must provide the forces Nato military commanders require," Bush said just before the summit began in Riga, many of whose inhabitants had left town to avoid disruption caused by the tight security.
"Member nations must accept difficult assignments if we expect to be successful," he said.
One Nato official said Supreme Allied Commander James Jones estimated that 26,000 of the total 32,000 troops in the Nato-led International Security Assistance Force [ISAF] were now "more useable" as a result of restrictions being eased.
He added that three nations had made initial pledges to send more troops, without giving details of how many or where they would go, and that several nations had pledged to raise their financial support for reconstruction in Afghanistan.
The Nato summit coincided with more violence in Afghanistan.
Two Nato soldiers and an Afghan policeman were killed in a battery of attacks on Tuesday. Two other soldiers with the ISAF and five Afghans were wounded in the day's violence.
The 37-nation ISAF did not release the nationalities of any of its casualties. It always waits for the home nations to make this announcement.
The soldiers who were killed were in a patrol that was blasted by an explosive device in Logar province, near the capital Kabul, the force said.