From time to time you see God signs like this quoting God. When people read them, nobody thinks God actually said these things. Even though they are usually written by Christians, nobody accuses the Christians of false prophecy either. The reason is because that would be a confusion of genre. The signs are not meant to be prophecy, so they can't be false prophecy.
On facebook, some people have this app where "God wants you to know..." something. The app posts a blurb written in first person from God's point of view that usually contains some shallow platitude or feel-good advice. But nobody thinks God himself is actually saying these things, and nobody intends for it to be taken as if he did.
I also see mock conversations between God and somebody else that Christians include on T-shirts, cards, books, or whatever that are supposed to illustrate some point. But none of these things are meant to convey what the author thinks God actually said. Nobody takes them that way, and nobody intends for them to be taken that way.
Do you ever wonder if some of the things in the Bible are that way? Maybe it's a genre, and maybe some of the "prophecies" in the Bible fall under that genre and are not meant to be taken as prophecy at all. I'm inclined to think apocalyptic literature (e.g. Daniel and Revelation) are like that. What do you think?