I agree with elklandercc on the point that hammer ons can easily (well not easily but what I mean is it is possible) be achieved on acoustic guitars. It just takes a matter of time to train your finger to hammer on at the right place at the right time.

If you're a fairly new guitarist you will find it really hard to hammer-on because of the high action (space between the fret and the string) and the string tension. You need to strengthen your fingers, which you can either do through lots of practice or getting something like the "gripmaster" (google it).

I think it's a good thing that you're starting on the acoustic like markc2005 said. It's good for improving your technique and finger strength, and you'll find the electric quite easy to get the hang of after that. You will need to get used to the fact that every single mistake is amplified on the electric though.

Hope that helped! :D