Acinetobacter sp. represent an important cause of nosocomial infections. Their resistance to some antibiotics, their ability to survive on inanimate surfaces in the hospital environment and their ability to produce biofilms contributes to their virulence. The aim of the study was to determine the antibacterial properties of cinnamon, lavender and geranium essential oils against bacteria of the genus Acinetobacter isolated from several clinical materials and from the hospital environment. A comprehensive evaluation of the susceptibility of Acinetobacter sp. clinical strains to recommended antibiotics was performed. The constituents of cinnamon, lavender and geranium essential oils were identified by GC-FID-MS analysis, and their Minimal Inhibitory Concentrations (MICs) against tested clinical strains were determined by the micro-dilution broth method. In addition, the effects of essential oils on the viability of human microvascular endothelial cells (HMEC-1) and glioblastoma cell line (T98G) were evaluated. Cinnamon bark oil was the most active against clinical and environmental strains of Acinetobacter baumannii with MIC values ranging from 0.5 to 2.5 µL/mL. The MIC values for geranium oil were between 7.5 and 9.5 µL/mL, and between 10.5 and 13.0 µL/mL for lavender oil. These essential oils can be best employed in the fight against infections caused by bacteria from Acinetobacter genus as components of formulations for hygiene and disinfection of hospital environment.