"Anyone can make value judgements about my work, but they cannot slander me, make things up, and tell lies and stupid stories," Mesic told reporters at his election headquarters.
Mesic said that independent candidate Boris Miksic slandered him by alleging on Wednesday that the French intelligence service had given Mesic a villa on the French Riviera as a gift.
"I've never heard greater nonsense. I thought he was a serious person. He has the right to make value judgements, but he will have to give money to the children in Nazorova Street for this," Mesic said, referring to a children's home in Zagreb.
Commenting on a statement by another rival, Slaven Letica, that if elected president he would have anyone who "dished out" transcripts from the President's Office prosecuted, Mesic said that Letica "should start with himself, because he was the first to sell transcripts".
The incumbent president also commented on the results of an opinion poll published in the Globus weekly, according to which the presidential race will be decided in a run-off. Mesic said he still believed that a new president would be chosen in the first round.