Vice-Prime Minister Hrihoriy Nemyria was speaking to the BBC a day after the ruling pro-Western coalition collapsed.
He said the priority was to re-establish a coalition with President Viktor Yushchenko`s Our Ukraine bloc.
Ms Tymoshenko and Mr Yushchenko were allies in the pro-Western Orange Revolution of 2004.
President Yushchenko pulled out of the ruling coalition after Yulia Tymoshenko`s bloc sided with the opposition to pass several laws that Mr Yushchenko saw as a threat to his presidential powers.
Asked whether Ms Tymoshenko was actively considering forming a government with Viktor Yanukovych, Mr Nemyria told the BBC`s Hardtalk TV programme: "The answer is no".
Ms Tymoshenko leads the second largest group in the 450-seat assembly, after Viktor Yanukovych`s Party of the Regions.
Mr Yanukovych has said that any new coalition should include his party.
President Yushchenko`s Our Ukraine left the government on 3 September.
Parliament now has 30 days to try to form a new ruling coalition. If those efforts fail, Mr Yushchenko can dissolve parliament and call a snap election.
"The worst-case scenario would be an early election in mid-winter," Mr Nemyria said.
"Still we are in the phase where we haven`t exhausted yet all the possible ways for reaching a strategic compromise."
Mr Yushchenko and Ms Tymoshenko led the 2004 Orange Revolution, which overturned the fraudulent presidential election victory of the pro-Moscow candidate, Viktor Yanukovych.
But since then, the two former allies have become bitter rivals, vying for power ahead of the 2010 presidential election.
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