I've read conflicting views of taking Creatine and then cups of green tea throughout the day. Creatine is less effective when taking with Caffeine and Green tea has caffeine within it. Green tea also acts as a diuretic, so would drinking a few cups of green tea throughout the day be problematic when taking Creatine Monohydrate?
I wouldn't worry about it.
Some of the initial research showing creatine's benefit to strength athletes had it mixed with tea, so I doubt there's anything to worry about.
I never give a second thought to mixing Creatine monohydrate with caffeinated beverages.
Look at it this way: creatine gives your muscles volume/gets em bloated, green tea flushes out excess water from your body. Opposite effects. Depends on your goals at the end of the day. Don't take too much caffeine though, if your goal is to get big and strong.