When Moria was getting beaten down, he asked Doflamingo if it was Sengoku who told him to eliminate him while Doflamingo states "Try Higher." What he means is, that there was a higher ranking marine(s) than Sengoku who had issued this order since they believed that Moria was too weak to be be a shichibukai. However we do not who the higher class is yet. It could possibly be the Gorousei. Kuma makes a statement to Kizaru along the lines that the Shichibukai answer to the WG, not to the Marines. So its the Gorousei that gave the order to Doflamingo.