Air carrier pilot reported a low altitude alert from ATC while inside the final approach fix.

Narrative

It was my leg flying into LGA on the RNAV (GPS) Y Rwy 13 approach. Autopilot was engaged and Approach mode active. Weather was clear and we were visual with the runway and airport. Correct altimeter 29.99 set. Fully configured and on speed. We were inside the FAF having checked and verified BROHR at 1;700 ft and about to make our final turn to line up on the runway when the Tower controller called and advised Low Altitude alert. He also called out the altimeter setting 29.99 which we both confirmed was set. I immediately clicked off the autopilot and both myself and the FO scanned instruments; MCDU (Multipurpose Control Display Unit) and outside aircraft to see if we were in fact below altitude. We both confirmed that the aircraft was on profile and everything appeared normal. Visually looking at the runway and PAPI's I also confirmed that I was on glideslope. The remainder of approach and landing were uneventful and normal. Both pilots discussed if anything could have been off and we couldn't determine any reason for the low altitude alert.I believe this was the first time for each of us seeing this particular approach into LGA as it didn't look familiar to me. We discussed this in the brief but also pointed out that the approach looked straight forward and nothing unusual stood out. We honestly don't think we were ever low on altitude but I would be very curious to find out the reason for the low altitude alert and if there was anything I did wrong.