Vučić has expressed a wish to visit the Jasenovac memorial centre privately, but has been denied clearance from the Croatian authorities to visit the site of the WWII concentration camp.
"We have learned unofficially that he wishes to pay a visit on Sunday, but without a formal announcement that should precede any visit, especially of this nature. No matter how discreet he may want it to be, it's not a private visit. It's a matter that has its political implications," Plenković told reporters after a meeting of the leadership of his HDZ party.
"We have said that it is not the right moment, nor is the methodology right. When the time comes and the conditions have been met, we can talk about it," he added.
He described the reaction from Belgrade, not just from the government but the media as well, as "hysterical," adding that Croatia is "inclusive and tolerant" and is not trying to score political points on this issue.
"The visit will come about when the time comes. A policy of fait accompli is unacceptable anywhere, including Croatia. At this point we concluded that this visit does not suit us," the Croatian prime minister said.
Earlier on Monday, Vučić said he had tried but failed to arrange with Zagreb a visit to Jasenovac three times, once in 2021 and twice in 2022. He said he was rejected because of the "internal political situation" in Croatia, with the explanation that his visit was not welcome.
"I know of his initiative from late February, March. We said that the time was not right for such a visit. After that there have been no contacts or discussions on this subject," Plenković said.
He added that at the end of February Construction Minister Darko Horvat was arrested on corruption charges, his father died, and the USKOK anti-corruption office were interested in Deputy PM Boris Milošević and Labour and Pension System Minister Josip Aladrović.
"We sent a message that it was not a good time for such a visit. As for September 2021, I tried to check it with my aides and we do not remember that. We will check it again," Plenković said.
He said that any visit that might have political consequences should be carefully arranged.
"It is important that we treat each other with respect and show that we are states. States communicate like people," Plenković said, adding that anyone wishing to visit someone should announce their visit.
He said that the matter would be discussed later on "when passions have cooled" and "constructive communication is established."