It is a while back since I studied it but I believe it was Austro-Hungaria that wanted to suppress the Serbs, they needed a guarantee that Germany would stop Russian interference. The Kaiser more or less turned a blind eye.
And I studied it at University in December, and you are incorrect.
The German's were incredibly afraid of Russia and it's industrialisation, they had to go to war but their experts told them they only had a window between 1914-1917 before it would be too late. Their battle plan required they defeat France before turning on Russia - and also involved going through Belgium to do so.
They tried twice to instigate a war between 1910-1914, this was their third attempt. They effectively forced the Austrians into the war with Serbia by insisting of draconian conditions and guaranteeing full backing. Even at the last, when the Kaiser yet again had cold feet, the Chancellor changed the text of his cable to the Austrians to force the war. Upon the declaration the German foreign office celebrated.
The German's started the war, coldly and deliberately.
fritz Fischer - Germany’s Aims in the First World War