In an interview with Belgrade's Danas of Thursday, he said he would visit Zagreb in the middle of the year following Croatian PM Ivo Sanader's "very important" visit to Belgrade late last year.
Kostunica said his meeting with Sanader would focus on every important issue aimed at improving Serbia-Montenegro-Croatia relations, including return of refugees and their property, affirmation of minorities' rights, and transfer of convicts.
He added that by the time of the meeting, last weekend's RSK episode would have been forgotten. RSK was an unrecognised statelet set up by Croatian Serb rebels in the early 1990s.
Kostunica said Serbia-Croatia relations should be built in accordance with every agreement signed since 1995, from the one on the normalisation of relations to the one on the protection of minorities, signed during Sanader's visit.
He added that everything outside those agreements was informal and could not improve relations or solve issues, including the RSK event in Belgrade last weekend.
Serbia's President Boris Tadic and Foreign Minister have also condemned the event.