If you've built a reliable detector, you've already built something that can intercept them. You just need to make a shroud around your detector and a tube facing your transmitter out of the same material.

There are ~65,000,000,000 neutrinos from the sun passing through each square centimeter of your hands every second as you read this. There are no materials on Earth that can reliably stop any given neutrino. For that, one needs densities greater than those generally found in stellar cores.

Neutrino detectors work by maximizing dumb luck through being both very large and very, very clean (low radioactivity). The transmitter-detector systems work by sending oodles of very energetic neutrinos at a well-defined time and looking for a rare coincident flash in the detector.

Any detector useful for communication is also an interceptor. The way we detect neutrinos now is not useful for communication.

If you're sending neutrinos at a known energy from a known location and in a narrow time-coincidence window, you can hammer most backgrounds way down.

The low detection rate isn't so terrible either -- one only needs the bits that are detected to be tradably-correct almost-all the time.

The hard part is arranging to make enough money to fund the accelerator and detector.