The potential of seventeen marine seaweed extracts (five Chlorophyceae, sex Pheophyceae, sex Rhodophyceae) was investigated to determine their antibacterial activity, aiming to evaluate their viability in pharmaceutical applications. The assessment of their bioactivity involved utilizing crude extracts from dried samples against five Gram-positive bacteria, one Gram-negative bacteria, yeast, and fungus using the disk diffusion technique. These samples were collected from Oualidia, situated along Morocco’s Atlantic coast. Out of the diverse macroalgae studied, 36% of the extracts exhibited activity against at least one of the tested microorganisms. This outcome strongly supported the notion of leveraging algae extracts as a promising source of antibacterial compounds. In particular, extracts from Cystoseira humilis, Bifurcaria bifurcata and Asparagopsis armata showed zones of inhibition greater than 17 mm. Purification of the compounds responsible for the inhibitory activity against several types of C. humilis microorganisms was performed using chromatography and thin layer chromatography (TLC).