"The main objective of the talks we are planning to have is the de-escalation, to find real ways how to de-escalate the situation," said Yurii Klymenko, Kiev's ambassador to the United Nations in Geneva, location of Thursday's talks.
"Ukraine is not going to discuss at this meeting the internal issues of Ukraine," he told reporters.
Moscow has demanded that pro-Russian separatists take part in the meeting, which marks a new diplomatic effort to defuse tensions between Kiev's pro-Western government and Moscow that have caused the worst European security crisis in decades.
The separatists' demands range from more autonomy through to recasting Ukraine as a federal nation, or joining Russia outright — as Crimea did last month in a referendum slammed by the international community, after a military takeover by Moscow.
But Kiev, which blames Moscow for stoking strife, has rejected the idea of having specific representatives of the country's restless south and east at the table in Geneva.
"We are not going to discuss the federalization of Ukraine," said Klymenko.
"We strongly believe that regions of Ukraine have to have more freedom, and now the government of Ukraine is very much committed to decentralize, to give more powers to the regions, but we are not talking about federalization," he added.
Since February's ouster of pro-Moscow Ukrainian leader Viktor Yanukovych, the Kremlin repeatedly has accused Ukraine's government of violating the rights of the country's ethnic Russian minority, and used this to justify its annexation of Crimea.
Russian Foreign Minister Sergei Lavrov on Tuesday warned Kiev against using force to quell the separatists, saying such a "criminal" act would undermine the planned talks.
Klymenko hit back, defending Kiev's efforts to halt the separatists' takeover of public buildings.
"This anti-terrorist campaign is directed not against the people, it's directed first of all against the separatists who are provoking violence in my country," he said.
He reiterated Kiev's stance that Russia has piloted the unrest, for example by sending in barely-disguised special forces to lead separatist groups, and bolstering troop numbers just inside Russia, stoking fears of an invasion.
Klymenko said that Kiev planned at the Geneva meeting to deliver "vast and concrete evidence" of Moscow's misdeeds on Ukrainian soil.
He also questioned Moscow's commitment to dialogue.
"It's very remarkable that this unrest, these separatist actions, are taking place just before the talks," he said.
"We are interested in talks, of course, because any talks are better than military confrontation," Klymenko.
"But we want to have to effective, result-oriented talks, not talks for talks."
Besides aiming to defuse tensions, Klymenko said a key goal was to try to repair key trade ties with Russia, which is Ukraine's main trade partner and gas supplier.