The Bosnia-born tactician does not believe that his team deserved to lose at Stadio Olimpico and paid credit to his players for the commitment they showed on the pitch.
"I compliment my players for the hunger and energy they put onto the pitch," Football Italia quotes Petkovic as saying. "It certainly was not a deserved defeat.
"We still believe we can qualify for the Champions League and must continue to believe. We play for the entire season and must always go out to win, as we tried to this evening.
"The break comes at the right time, even if many of our players will go off on international duty. After the break, with different players available, we will perform differently."
Lazio have now slipped to seventh in Serie A.