The European Union said it took steps to be "technically ready for the possible signing" of an association agreement with Ukraine at a meeting later this year in Lithuania.
"The EU has underlined that it will only sign if Ukraine creates the necessary political circumstances," the commission said.
Conditions range from addressing concerns from last year's parliamentary elections to tackling issues of selective justice.
October parliamentary elections in Ukraine were viewed by EU observers as a step back for the former Soviet republic.
European leaders have expressed concern about the detention of former Prime Minister Yulia Tymoshenko and her allies.
The European Court of Human Rights said in April that some of Tymoshenko's rights were violated in prison. She was sentenced in 2011 to seven years in prison after being convicted on charges she abused her power in a natural gas deal with Russian energy company Gazprom.