"Euro membership is irrevocable," Breidthardt stated during a press briefing.
She refused to speculate on the forthcoming snap elections in Greece on January 25 which may determine whether the country intends to stay in the eurozone.
She also noted that the European Commission expected the euro to grow as, having proved its resilience, it was "here to stay."
On January 1, Lithuania became the 19th EU member state to adopt the euro.
Alongside Lithuania, the eurozone includes Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Luxembourg, Malta, Netherlands, Portugal, Slovakia, Slovenia, and Spain.