negatively regulates antisense RNA transcription negative regulation of DNA-templated transcription regulation of antisense RNA transcription negative regulation of antisense RNA transcription GO:0060195 biological_process Any process that decreases the frequency, rate or extent of the synthesis of antisense RNA, an RNA molecule complementary in sequence to another RNA or DNA molecule, which, by binding the latter, acts to inhibit its function and/or completion of synthesis, on a template of DNA. biological regulation