The statement was made during a meeting with Yulia Tymoshenko, the leader of Batkivshchyna party.
"We have great expectations regarding the new parliament. The creation of such a wide coalition looks hopeful, but I'd like to underline that there are no excuses for not introducing reforms. Fighting corruption and decentralization of power are key factors right now," Mr Hahn said, as quoted by the party's website on Thursday.
Earlier in the day, five political factions that made it to the Ukrainian parliament following the October 26 elections created a coalition. The five parties are the Petro Poroshenko Bloc, People's Front, Samopomich, Radical Party, and Batkivshchyna.
The Opposition Bloc, the sixth party that passed the electoral threshold, did not become part of the coalition due to "considerable political disagreements".
EU Commissioner Urges Kiev to Bring Ukraine Closer to Europe by Changing Business Climate
"We have the Association Agreement, and Ukraine should, as a matter of fact, change the business climate in the country, as foreign investors are ready to work actively and are interested in coming or returning to Ukraine for developing businesses, creating new job conditions, and if it will be so, Ukraine will automatically get closer to the European Union," Hahn told journalists in Kiev as quoted by UNIAN news agency.
Hahn said that the European Union is ready to aid Ukrainian politicians with state development, adding that the opportunities for creating jobs and improving the living conditions are Kiev's most urgent challenges.
The Ukrainian government is seeking closer ties with the European Union. In September, the Ukrainian and EU parliaments ratified an association agreement. The treaty presupposes political and economic association between the sides.
In mid-November, the European Union and Ukraine signed an agreement to launch an EU advisory mission which will assist Kiev in rebuilding the country's civilian security sector, including the police system.