The West must be prepared for "more concrete action and determined sanctions" against Russia over the situation in Ukraine, Andrii Deshchytsia, the country's acting foreign minister, told CNBC.
"The West is doing quite well. The sanctions that were imposed on Russia are a good step forward," Deshchytsia, a former diplomat brought in after the unseating of the Kremlin-backed Yanukovych regime in February, said.
He added that "if Russia will not stop" tougher sanctions would be needed.
Tensions over the parts of Ukraine with substantial Russian-speaking populations have threatened to spill over into military action this week. Pro-Russian separatists have taken over government buildings in several cities in eastern Ukraine. On Wednesday, protesters in the city of Luhansk asked Russian President Vladimir Putin for help.
"We are very much concerned...It is our view that what happened in Crimea may be repeated in eastern Ukraine," Deshchytsia said.
"I do not see any grounds for civil war in Ukraine. We do not need any military protection from Russia."
Russia annexed the Crimea region of Ukraine last month after a referendum which some Western powers condemned as undemocratic.
Deshchytsia said the Ukrainian administration is hoping to "implement original government reform and give more power to the regions" - a possible sop to protesters.
U.S. Secretary of State John Kerry has accused Russia of deliberately fomenting unrest in Ukraine, and called the protests an "illegal and illegitimate effort to destabilize a sovereign state."
Kerry and his Russian counterpart, Sergei Lavrov, spoke over the phone Wednesday night in which they urged all sides to refrain from violence in eastern and southern Ukraine, the Russian foreign ministry told Reuters.
The protests are also a distraction from the vital job of fixing Ukraine's economic woes.
Deshchytsia criticized Russia and state-backed gas company Gazprom for hiking the price of Russian gas sold to Ukraine, one of many factors hurting the country's economy.
Next week, there will be talks between Russia, Ukraine, the EU and U.S. over the situation - although the U.S. doesn't "have high expectations for these talks," according to Victoria Nuland, the US assistant secretary of state.
During Wednesday night's phone conversation, Lavrov told Kerry that any four-way talks between representatives of Ukraine, Russia, the United States and European Union must focus on fostering dialog among Ukrainians and not on bilateral relations among the participants, Reuters reported.
Presidential elections on May 25 are also expected to be a potential flashpoint for unrest.