Abstract Saharan soil samples collected in El‐Oued province have been investigated for actinobacteria as a valuable source for the production of bioactive metabolites. A total of 273 isolates were obtained and subjected to antagonistic activity tests against human pathogenic germs. A strain with a broad‐spectrum antimicrobial activity was selected and identified as Nocardiopsis dassonvillei GSBS4, with high sequence similarities to N. dassonvillei subsp. dassonvillei T X97886.1 (99%) based on polyphasic taxonomy approach and 16S ribosomal ribonucleic acid gene sequence analysis. The GSBS4 ethyl acetate crude extract showed strong antibacterial activity towards pathogenic bacteria and Candida albicans . It inhibited biofilm formation by Staphylococcus aureus and methicillin‐resistant S. aureus with minimum inhibitory concentrations estimated at 0.144 and 1.15 mg·mL −1 , respectively. A 44% biofilm reduction was obtained for S. aureus and 61% for Pseudomonas aeruginosa . Furthermore, phenols composition of the crude extract showed a significant dose‐dependent antioxidant activity by α‐diphenyl‐β‐picrylhydrazyl (57.21%) and 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonic acid) (64.29%) radicals scavenging assays. Although no inhibition was obtained on human coronavirus human coronavirus (HCoV) 229E and on model enterovirus (poliovirus 1) infection, a dose‐dependent increase in cell viability of HCoV 229E‐infected cells was noticed as the viability increased from 21% to 37%. Bioassay‐guided fractionation of the crude extract gave a fraction showing antibacterial activity, which was analyzed by liquid chromatography‐electrospray mass spectrometric technique, providing structural features on a major purple metabolite.