Any of the editors which edit AVCHD (e.g. Ulead VS, Sony Vegas) can convert it to DV-avi. But as you have Premiere you probably don't want to buy another editor just to do the converson.
I've heard good things about VoltaicHD, I think it will do it, and it's cheap. It says it will convert to avi, not sure if that includes DV.
http://shedworx.com/?q=voltaichdpc