Utiashvili said Georgian police did not return fire and that the situation in the area was calm.
He said the officer had died in hospital from wounds to the head and throat.
A spokesman for Russian forces in South Ossetia, who wished to remain anonymous, said the Russian side had not been involved in a shooting and was working with Georgian police to find the possible culprits.
"At the request of the Georgian side servicemen from units of our peacekeeping forces together with Georgian police are continuing the search for persons possibly involved in the killing of a policeman," he said.
Casting doubt on whether a killing had occurred, he said: "Georgian police have so far not presented the body."
Underlining the tensions in the area, a foreign ministry spokesman in Moscow accused Georgia's military of "provocative actions" and said Russian forces would return fire if necessary.
Alexei Nesterenko said: "Georgian soldiers are taking provocative actions near our observation posts. These provocations are intended to make us defend our soldiers."
Separatist authorities in South Ossetia also denied involvement in the incident.
"We have nothing to do with this incident," Irina Gagloyeva, the head of the press and information committee, said by telephone from the breakaway capital Tskhinvali, 30km north of Karaleti.
Gagloyeva said the closest Ossetian-populated village was 4km from the area, and suggested the incident may have been the result of "infighting" between Georgian police and army.
Russia agreed on Monday to withdraw its soldiers from 'security zones' outside the separatist regions of Abkhazia and South Ossetia within a month.
The troops pushed into undisputed Georgian territory last month having poured over Russia's southern border into breakaway South Ossetia to stop a Georgian assault mounted to retake the territory from pro-Moscow separatists.