It worked, this is what I did, First I used Glide to load my img, then I created an animation like so:
final ScaleAnimation growanim = new ScaleAnimation(1.0f, randscale), 1.0f, 1.0f, Animation.RELATIVE_TO_SELF,0.5f,Animation.RELATIVE_TO_SELF,0.5f);
growanim.setDuration(randomDuration);
growanim.setRepeatCount(-1);
growanim.setRepeatMode(Animation.REVERSE);
growanim.setInterpolator(new AccelerateInterpolator());
img.setAnimation(growanim);
growanim.start();
randomDuration = random.nextInt(2000 - 100 + 1) + 100l); --> random times.
randscale = random.nextFloat()*0.5f)+0.3f);---> random scales.
Thank you all for your help.