If the PTZ is used with presets, and the PTZ supports this, save the preset after manually focusing. This can stop the AF from trying to focus on the lights.
How about a properly-colored filter to block the blue light? A slight reddish tint should do it - if you can find out the exact wavelength of the LEDs, any good camera shop should be able to tell you (and sell you) the proper tint for maximum effectiveness, so you could use a lower-density filter and reduce the effect on the overall view coloring (AWB may be able to compensate to some degree). As far as masking, I doubt that would work, as I believe most cameras implement masking as an "overlay" on the output video - it would be processed in AFTER the autofocus.
Frank, I don't know if that would impact / block out the area from the camera's autofocus. It's worth checking. Thanks!
Did you try masking out the Blue light in the PTZ menu? I dont know if this would work. It's just a guess.