His conciliatory comments in the northwestern town of Lutsk were however overshadowed by a security breach after the ceremony when a young Ukrainian man walked up to him and slapped a raw egg on his shoulder. The president was not hurt in the incident.
While little known outside eastern Europe, the bloodshed in the Nazi-occupied Volhynia and Galicia regions in the west of modern Ukraine in July 1943 has strained ties between Ukraine and Poland.
Komorowski, joined by Ukrainian Deputy Prime Minister Kostyantyn Gryshchenko, said the past should not endanger the countries' friendship.
"An honest interpretation of the past should serve reconciliation and cooperation between our peoples and our two independent states," said Komorowski.
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"I hope that this wound between our brotherly nations heals quicker," he said.
Komorowski hinted that Moscow was the only winner when Poland and Ukraine feuded.
"We should not forget that only a third party -- that has always threatened our independence and freedom -- has won when the Ukrainian and Polish peoples have been in conflict."
"We have no reason to argue, nothing should separate our states. We have one aim, a common European future," he said.
The attacker, hiding an egg in his hand, walked up to Komorowski after the ceremony, bypassing security.
The man broke the egg on Komorowski's shoulder but the president appeared unfazed and swapped his soiled jacket for another.
The man -- a Ukrainian who has not been named -- has been detained by police. It was not clear what his motives were.