I was playing last night and this guy attacked my Red Star...

I played Titans Tower and dropped Raven to juice him up so he would back his Ra's Ghul...

He chained Tower of Babel, is TT negated?

Well if he is attacking you then it is his attack step. Tower of Babel only works on each players attack step so you being the defender would be unaffected at that moment.

But, if you were the one attacking then yes the Titan's Tower affect would have been Negated.