Yep, he did, at least if you trust the
Ainulindalë (which, by the way, was composed by our friend Rúmil):
The Silmarillion, Ainulindalë wrote:Then Ilúvatar [=Eru] spoke, and he said: 'Mighty are the Ainur, and mightiest among them is Melkor; but that he may know, and all the Ainur, that I am Ilúvatar, those things that ye have sung, I will show them forth, that ye may see what ye have done. And thou, Melkor, shalt see that no theme may be played that hath not its uttermost source in me, nor can any alter the music in my despite. For he that attempteth this shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined.'
EDIT: There's obviously room for a little bit of interpretation there: Melkor can't alter the music [=creation] against Eru's will, and the ultimate source of Melkor's theme is Eru, but you could interpret that as "Eru created Melkor, so everything Melkor does has Eru as its ultimate source, and Melkor did indeed alter the music, which was contrary to Eru's original plan but allowed by him anyway." Depends on whether or not you think the Ainur have free will, I suppose, which is a whole fraught topic that I don't have the Tolkien-knowledge to comment on.