Trackpad issue

Have you applied all available Software Updates via the Mac App Store?
I guess you do not have a late 2013 MacBook Pro with Retina Display this update applies to?

 

I had this issue with a mid-2012 MBP (non-retina). Looking for solutions, I found that there is no universal fix. Diagnostics range from swollen batteries to dirty trackpads, and solutions vary accordingly. They worked for some people, but not for others.
I use my MBP on the road a lot and it gets quite dirty, so cleaning looked like a reasonable solution. I cleaned the trackpad thoroughly and checked for particles on the edges of the trackpad. I used a toothpick. This fixed some of the problem, but did not solve it completely.
Eventually, repairing permissions fixed the problem for me. I do not know why, but you may want to try it.
If the above does not work, I suggest you take it to service.