"It was not a good game for us on Saturday but we should not go crazy," Khedira told a news conference at Germany's pre-Euro 2012 training camp in the south of France.
"We should not ignore the result but we should equally not overestimate it. We can still win the tournament."
Khedira is expected to resume his midfield partnership with Bayern Munich's Bastian Schweinsteiger that helped Germany finish third at the 2010 World Cup in South Africa.
Schweinsteiger was one of eight Bayern players who missed Saturday's match after coach Joachim Low gave them extra time to recover from the disappointment of losing on penalties to Chelsea in the Champions League final on May 19.
"The Bayern players were wounded but they are now full of anticipation for the tournament. They are fully focused," said Khedira.
"He laughs normally, he speaks normally, he is just normal," he added, referring to Schweinsteiger who missed his spot-kick in the Champions League shootout.
Low will announce his final 23-man squad on Tuesday, cutting four players from his preliminary list.
Germany play their last Euro 2012 warm-up against Israel in Leipzig on Thursday ahead of Group B matches against Portugal, Netherlands and Denmark in Ukraine and Poland.
‘After Manchester City’s recent form, maybe they’re the underdogs against Manchester United!’ Former Red Devils defender on this weekend’s derby
‘Arteta, Alonso, Emery, me… none of us were physical players – we needed the understanding of the game. That probably helped us move into management’: Premier League boss reveals reasons for natural career progression
