Maybe you should specify the flavor of Blast you are referring to. Chances are you are talking about NCBI web-based Blast. There I don't know an option to exclude a specific strand.
If you are using Blast in command line, there is an option to specify the query strand. Otherwise, filtering the output results would be pretty straightforward using 'grep' or 'gawk' commands. Same strategy could be easily applied if you download the web results into a file.