You may not contact the person directly to try and directly pay it off. Even if you did pay the person directly, that technically wouldn't absolve you of the restitution order because there is a still a court order requiring you to make payments through the clerk. Likely, the person receiving the restitution and so it is likely that you have a condition of your probation to not contact the victim. Try making larger payments to the clerk so that more of it goes to the restitution amount and less is going to transaction fees.
This is not to be considered legal advice nor does an attorney-client relationship exist.
One way you might be able to deal with this is to file a motion to modify your probation to state that all payments are to go to paying restitution first and address this issue with the Court. I have had judges specifically state this in the order of probation to ensure that is paid before all other fees and costs. In addition, it brings it before the Court for an accounting of your matter.