Tymoshenko, leader of the All-Ukrainian Union "Fatherland" political party, said during a meeting in Ireland with European leaders Ukraine should sign agreements with EU immediately.
"The people of Ukraine fought for this right at the cost of the lives of our patriotic men," she said in a statement posted on her website.
Tymoshenko's political adversary, ousted President Viktor Yanukovych, a Kremlin ally, in November decided to suspend efforts to sign free trade and association agreements with the EU to protect economic ties with Russia. The decision sparked a major revolt that led to his ouster last month.
EU leaders met Thursday in Brussels in an extraordinary session to discuss the developments Ukraine's Prime Minister Arseniy Yatsenyuk, who hails from Tymoshenko's political party.
In a statement, the EU leaders said they were committed to embracing Ukraine.
"It was decided to sign the political chapters of the [association] agreement before the Ukrainian elections May 25," they said.
The ouster of Yanukovych has strained the relationship between Russia and Western governments.
Russian President Vladimir Putin said he'd use force to protect national interests in Ukraine only as a last resort. Herman Van Rompuy, president of the European Council, said Thursday there would be "serious consequences" if Russia failed to respect Ukraine's sovereignty.