Actually, I've tried that, he attacks you, and, unless something goes wrong (perhaps you're under leveling the game or some such) you survive and automatically counter attack with a normal strike, so even not attacking is out the window.
To be fair though, since that was a battle of minds and wills, supposedly meant to showcase Cloud's triumph over Sephiroth's will or something cliche like that, there are any number of explainations for why he was so much weaker in that fight.