Kind of. The GPS signal portfolio is evolving. In the beginning, the encrypted code was broadcast on two frequencies, L1 and L2. The public code was only on L1. So you could in theory jam just L1 to block the un-encrypted portion, but why would you?

In recent years GPS modernization means satellites have been using new codes on L2 (L2C) which are un-encrypted. Only about 18 of the satellites carry that capability at this time.