He was speaking at a conference on Croatian-Italian relations from 1915 to 1947 which was organised by the Zagreb Faculty of Philosophy History Department.
Mesic said Croatia and Italy were resolving outstanding issues bilaterally, honouring existing agreements.
He added, however, that relations in recent years had been burdened by issues stemming from different perspectives of events between 1915 and 1947, and by the questioning of some provisions from peace treaties signed after World War Two.
Mesic said it was superfluous to point out the divide that fascism had caused between the peoples in Istria with its totalitarian monoethnic policy.
That continued in the first two years after WWII on the territory of the first Yugoslavia, he said, adding that under the Rome agreements between the 1941-45 Independent State of Croatia (NDH) and Italy, Italy remained in power in Istria and a greater part of Dalmatia.
Under the Pazin decisions adopted after Italy's capitulation in 1943, Istria was returned to Croatia, which was then part of Yugoslavia, Mesic recalled, adding that in May 1945, after the liberation of Rijeka and the advance of the partisans to Trieste, crimes were committed against Italians that nobody in Croatia was denying.
"We aren't turning a blind eye to those crimes nor are we justifying them. They are a historical fact. The quantitative and other aspects of those crimes have to be objectively established," said Mesic.
Just like no one can accuse the Italian people for crimes committed by the Italian side, no one can accuse the Croatian or any other people for crimes committed by the partisans, Mesic said, adding that responsibility was always individual and not collective.
The book on WWII should be closed on the basis of what was done afterwards with the Paris, Rome and Osimo treaties which settled, among other things, the issue of damages to Italians who left the then Yugoslavia, said Mesic.
Under the Treaty of Osimo, which Croatia inherited as one of the successors to the former Yugoslavia, Croatia should pay USD35 million for that purpose into an account that the Italian government should open, Mesic said.
He added he had accepted an invitation by former Italian President Carlo Azeglio Ciampi to meet with the presidents of Slovenia and Montenegro, to take several steps to close the book on WWII and to bow down to the victims.
Mesic suggested that a memorial centre should be opened in Istria to appropriately mark and close the chapter of relations between the end of WWI and the end of WWII.
Mesic recalled that he and Italian President Giorgio Napolitano had issued an agreed statement on this matter which said that a recent commemorative speech by Napolitano had not been critical of Croatia or had any intention to bring into question the 1947 Treaty of Paris or the Treaty of Osimo.