No, GIF only supports 256 colours (8bit).
24 bit colour is around 16.7 million colours.
However, if all you want to do is lower the filesize of a gif animation.. It can be done pretty easily by either lowering the amount of colours used or resizing the dimensions.
Post the animation here, me or another member will try our best at compressing it.
If you've got Imageredy, you can compress it yourself. Go window > optimize to bring up the optimize pallet.

Press the arrow, and then choose "Optimize to filesize", like in the image above. Put in the filesize you want, and then go File > Save Optimized. If it looks terrible, then chances are you won't be able to get it down to that filesize by just removing colours, you'll have to also do something else, like changing dimensions, or removing frames.
thats not in ps cs tho..