Berlin was afraid that France might start a war to get the lost provinces back.
Thus, Bismarck tried to keep France isolated in Europe. He knew that France would need a partner or two to fulfill this ambition. Bismarck knew that Germany could deal with any single aggressor - but as a team they would have the advantage.
France certainly deserves its share of the blame. Not saying the Germans and Austro-Hungarians weren’t blameless neither. All three were in the wrong, and they had to ultimately drag Britain, and subsequently the US, into it.
Not to mention Britains desire to boot the Turks out of the Middle East. It probably would have been better had the Arabs stayed under Turkish rule, compared to what we have today over there.
Bismark’s strategy and goals for Germany were defensive after 1871, with Germany to become a peaceful status quo power. On accession, Kaiser Wilhelm though favored a policy of aggressive colonial acquisitions and building Germany a large and potent army and navy that would assure her primacy in Europe against France and Britain, one way or another. Wilhelm soon clashed with and dropped Bismark, adopting a program that set Germany toward WW I.