> anyway, for the compressed teas, is there any character [or
> characters] for compressed tea in general in chinese?

Yes, there are words to mean compressed tea in Chinese. But the
translation below is incorrect. I wouldn't trust bablefish or any
online translator. They all give really muddled results.

> babelfish says:
> 浓缩茶 for the simplified
> 濃縮茶 for the traditional
>
> is it correct? would they understand me?

This actually means "concentrated tea" or "condensed tea".

For compressed tea, you want these characters:
紧压茶

In Pinyin it's jin ya cha.