Read this from the FAQ on this website: FAQ: Why does horizontal motion stutter (judder) in my movies, such as during pans?
If you have the original AE file the fix is fairly easy. If you have only the rendered footage and there are not sub pixel interpolation problems with the move you may be able to fix the problem by putting the footage in a higher frame rate comp and interpreting the footage to match. For example, if the rendered footage is 23.976 fps then change the interpretation to 29.97 by selecting the footage in the Project Panel and choosing File>Interpret Footage. Then put the footage in a 29.97 fps comp and render and test.