1) I agree with hamid159, just don't connect a load that will draw more than 2 amps.
2) If you are worried that the load may try to draw (much) more than 2 amps, then I agree with m.naveed, except that you would need to use a fusefor more than 2 amps. Check out the datasheet to see how long a given fuse can run at or near 2 amps before blowing.
3) Are you asking for a circuit that will regulate current flow to two amps? Then what you want is called a current source or an adjustable current source. I don't have one to post right away. Google it or search the forums.