"A scenario whereby President Yanukovych loses power seems unlikely," Donald Tusk has told the TVP broadcaster.
"All the analysis indicates Yanukovych will be the official partner for Poland and Europe for another year and a half," Tusk added, referring to elections in Ukraine scheduled for March 2015.
Tusk attended a meeting of the National Security Council on Monday, called by President Bronislaw Komorowski to discuss the political situation in Poland's eastern neighbour.
Leaders of Ukraine's three main opposition parties demanded snap presidential and parliamentary elections on Monday as pro-EU protesters blockaded government buildings in Kiev.
Opposition parties said they would try and force a vote of no confidence in the government in parliament on Tuesday, with world heavyweight champion boxer-turned presidential candidate Vitaly Klitshcko predicting at a press conference that President Yanukovych will sooner or later “take a trip abroad” - meaning he will flee to Russia.
"We will continue having dialogue with the opposition, which is an obvious and natural partner, but we also need to talk constantly with the Ukrainian authorities," PM Tusk said, however.
"Yanukovych must be the partner to talk to, because he is the democratically elected president of Ukraine," Tusk said on what the next steps will be for Poland, who has been leading the drive, with Sweden, in the EU to bring ex-Soviet states like Ukraine close to the West and away from Russia, which the Polish prime minister said "has been putting a lot of pressure lately on not just Ukraine but Moldova [which did sign trade and other deals with the EU last Friday]".
Meanwhile, Russia's president Vladimir Putin has claimed that the protests "have little to do with EU-Ukraine relations" but were planned ahead of elections.
"This has all been prepared for the presidential election. And that these were preparations, in my opinion, is an apparent fact for all objective observers,” Putin is quoted by Russia Today television as saying.
RIA Novosti reports that Prime Minister Nikolay Azarov said following a meeting of ambassadors from EU states and the US in Kiev on Monday that his government was still negotiating with Brussels on signing an associate agreement.
“We’d like to discuss the provisions, which bother us. We’d like our initiative to be treated attentively and maybe we’ll be able to achieve compromise,” he said.