Air carrier flight crew reported an NMAC with a helicopter on approach.

Narrative

When we checked in with approach; ATC changed our arrival and approach from XXL to XYR. I was the flying pilot and we were below FL180 so the FO put the RNAV XYR into the FMC; set up the RNAV parameters; got landing data and briefed the engine out procedure. We briefed the runway exit and taxi plan. We were cleared for the RNAV approach prior to ZZZZZ and proceeded on the approach. We switched to tower and were given the visual approach and cleared to land. Tower also advised of several helicopters flying over the strip west of the final. Prior to ZZZZZ1; I disengaged the auto pilot; lined up on the extended centerline and descended. About 3600 feet we received a DESCENDING RA that lasted until approximately 3300 feet. The helicopters wee 100 feet above our altitude and the FO had a visual on the traffic. I continued my descent following the RA commands for the runway. My glide path went to 4 red lights on the PAPI and I corrected to 3 red and 1 white lights. I continued the approach to a normal landing. Once clear of the runway; I advised the Tower controller that we received an RA. His response was nonchalant at best and he stated that he advised us of the traffic. We taxied to the gate as normal.