Premiere can not recognize and edit AVCHD video files. But it can read and notice some common video formats, like MOV and MPEG.
So you should do some conversion to your Panasonic AVCHD video files to MOV editable by Premiere.
As for AVCHD video converter, have a try Aunsoft MTS Converter for Mac which can decode AVCHD video files to any format you need, including MOV,AVI,MPEG and ect. with lossless of original video quality.
Good luck.
Oudinmel