He said everyone must be equal before the law and that he expected all institutions to do their job so that those who were innocent could be released and those who were guilty be held to account.
Mesic was speaking to the press after the presentation of a book about Bosnia and Herzegovina.
He also commented on alleged secret foreign accounts used to buy arms for Croatia during the 1991-95 war.
"There are those who would like to block the investigation into those secret accounts," Mesic said, adding that "if I see that this is really so, I will speak publicly about all the elements so that the truth about it can be uncovered".
In a recent statement about the accounts, Mesic said that relevant institutions must determine the amount of money someone had been in charge of, what they had bought with it and how much money had ended up on someone's private account.
He said there were still hundreds of millions on private foreign accounts, that this meant that Croatia had been robbed, and that this was mainly money earned from the sale of flats and money from Croatian emigrants.