BERLIN—German Chancellor Angela Merkel on Thursday dashed hopes Ukraine would be awarded a visa waiver, alongside the prospect of eventually becoming a European Union member, at the EU’s Eastern Partnership summit that starts later Thursday in Latvia.

“The Eastern Partnership isn't an EU enlargement policy instrument,” Ms. Merkel speaking in an address to Germany’s lower house of parliament on the coming EU summit with its Eastern European partners and the summit of the Group of Seven nations’ leaders in Germany next month.

Ukraine Foreign Minister Pavlo Klimkin had said earlier in an interview with German daily Die Welt that he expects the EU’s Eastern Partnership summit with six former Soviet republics to promise a visa waiver to Ukrainians from next year and to give Ukraine the promise to be a potential EU member state.

“Easing visa restrictions is only possible once all preconditions have been met,” Ms. Merkel said.

Pointing to a recent report by the European Commission on Ukraine and Georgia, Ms. Merkel said these countries’ efforts “aren't yet sufficient and a lot still needs to be done” before the commission issues a fresh assessment, due at the end of this year.