Actually, Germany did nothing until Russia mobilized against them FIRST, just like France mobilized against Germany FIRST (truth be known it was the French ambassador who was pushing the Russians to attack Austria in the first place).
The simple fact is that the problems were totally between Austria and Servia and no one else. It was Russia, prodded on by the French, who stuck their nose in and started to spread the hostilities. When Russia, unprovoked, moved against Austria, Germany was bound to defend their ally. An ally, by the way, whose war against Serbia was totally justified. The Germans gave the French ample opportunity to declare their neutrality and keep peace in the West -they failed to do so. The French were looking for any opportunity to get Alsace-Lorraine back from Germany after the spanking they got in 1870; just as Britain was looking for any opportunity to remove German economic/colonial competition.
Frankly, I see nothing "humanitarian" about American fat cats getting rich selling arms, ammunition and all manner of supplies to the British while thousands of Germans are starving to death, all the while pretending to be "neutral". I see no sense in condemning Germany for invading Belgium when before the war, Wilson had invaded numerous countries in Latin America for the sake of American business interests. The warring powers were all on the verge of exhaustion by the time America declared war anyway, it could not have gone on much longer regardless of what the US did. All Wilson accomplished was to give the Allies overpowering force in the final days to inflict on the Central Powers the most atrocious, humiliating and ultimately dangerous peace terms they could force out.
Oh yes, poor little Germany, put upon by all those evil democratic, popular regimes, including France, which the Hollenzollerns invaded and took land from by force. (I would note that the creation of the German Empire was not sanctioned by long prescription, but was a pure Realpolitik creation of the Chancellor Bismarck. In addition, they were not Catholic, so they don't even fit the Catholic monarch paradigm.) Yes, we shouldn't restrain the great German Uebermensch as it teaches a lesson to less advanced societies that don't practice autocratic monarchism, that most blessed of regime types! If you think democracy and America is so evil, I suggest you go live elsewhere if you are American, where your authoritarian and servile (if you are not a ruler or aristocrat) instincts will be better appreciated.