The ability of several N-phenyl-1H-pyrazole-4-carboxamide derivatives and other pyrazoles opportunely modified at the positions 3, 4 and 5, to reduce the formation of the biofilm in some Staphylococcus aureus strains (ATCC 29213, ATCC 25923 and ATCC 6538) were investigated. All the tested compounds were able, although to a different extent, to reduce the biofilm formation of the three bacterial strains considered. Among these, the 1-(2,5-dichlorophenyl)-5-methyl-N-phenyl-1H-pyrazole-4-carboxamide 14 resulted as the best inhibitor of biofilm formation showing an IC50 ranging from 2.3 to 32 μM, against all the three strains of S. aureus. Compound 14 also shows a good protective effect in vivo by improving the survival of wax moth larva (Galleria mellonella) infected with S. aureus ATCC 29213. These findings indicate that 14d is a potential lead compound for the development of new anti-virulence agents against S. aureus infections.