I had the same problem, but, looking on the web, I found a solution.
Simply, I installed SAGA from other repository (http://gis.stackexchange.com/questions/70283/installing-saga-gis-2-1).

Try the following commands from a command line:

sudo add-apt-repository ppa:johanvdw/saga-gis

sudo apt-get update

sudo apt-get install saga

I hope it works.