4.13 The whole universe beginning with Brahma and ending with a cluster of grass, with the system of four stations divided according to Sattva and other Gunas and by actions like self-control corresponding to the Gunas, was created by Me. The mention of 'creation' is for illustration. The universe is protected by Me alone and is withdrawn by Me alone. Know Me to be the creator of his manifold actions of creation etc., but at the same time to be non-agent.

Sri Krsna explains here how this is possible.