The present study was aimed to identify the antibacterial potential of biosynthesised silver nanoparticles using different plant parts (leaves, bark and root) of Avicenna marina mangrove plant. Of the selected three different parts, the leaf extract showed the maximum synthesis of silver nanoparticles. The in vitro antibacterial assay (100 μg disk−1 concentration) showed the results of maximum zone of inhibition with the E. coli (18.40 ± 0.97 mm), and minimum (10.87 ± 1.33 mm) zone of inhibition with S. aureus but the concentrations of MIC and MBC values ranged between 6.25 and 50.0 μg ml−1 between the selected bacterial strains. The FTIR results of most potent leaf extract-synthesized silver nanoparticles showed the prominent peaks (620.967; 1,061.02; 1,116.58; 1,187.94; 1,280.50; 1,353.79; 1,384.64; 1,598.50; 1,629.56; 2,854.14 and 2,927.42) in different ranges. Further, the results of XRD analysis showed the 2θ intense values (38.11 and 70.57) within the ranges of Bragg’s reflection. In addition, the AFM analysis showed the results of particle sizes (71–110 nm), particle roughness (11.8 nm), maximum height of the particle roughness (111.8 nm), and average maximum height of the particle roughness (57.5 nm). It can be concluded from the present findings that, the biosynthesis of silver nanoparticles from the leaf extract of A. marina can be used as potential antibacterial agents.