Control of plant bacterial diseases remains difficult due to the limited availability of efficient plant protection products with reduced negative effects either in the environment or with human and animal health. In order to reduce the usage of chemical pesticides alternative strategies for controlling plant pathogens and improve plant disease resistance are promoted. The aim of the study was to investigate the antibacterial activity of some natural compounds (plant extracts of Tamarix ramosissima, Rosmarinus officinalis, Chelidonium majus, Silybum marianum, Satureja hortensis essential oil and propolis) against bacterial ring rot pathogen, Clavibacter michiganensis ssp. sepedonicus (Cms). An agar diffusion method was used for the screening of the inhibitory effect of natural compounds on bacterial strains’ growth. Minimum inhibition concentrations (MICs) were determined by a twofold serial dilution method. The anti-pathogenic activity was investigated by the study of anti-biofilm activity of natural substances. The analyzed natural substances showed a good microbicidal activity and anti-biofilm activity. The results obtained from this study may contribute to the development of new bio-control agents as alternative strategies for prevention and control of ring rot pathogen.