Cotton plants grown in the greenhouse under natural day length in the summer were watered with four different water regimes (daily, every other day, twice a week and once a week). Bemesia tabaci counts (adults and nymphs) were recorded on the whole leaf sample of the lower (abaxial) surface of the cotton leaf for each treatment. Plant physiological characteristics such as leaf water content which represented by Fuel Moisture Content (FMC) and Equivalent Water Thickness (EWT), were calculated from the leaf fresh weight (FW), dry weight (DW) and leaf area (LA) were also recorded. Cotton plant height and soil moisture content (TDR) were also recorded during the watering and drought phase. Plant growth was significantly different at the four watering levels but no significant difference of the mean numbers of B. tabaci adult, nymph and insect population (P=0.1354), (P=0.1712) and (P=0.2534), respectively in all levels of watering. However, after the plants were not receiving regular watering during the drought phase (results after day 56) significant differences in the mean numbers of B. tabaci adult, nymph and insect population were observed (P =0.0001), (P = 0.0009) and (P =0.0001). Multiple regression analysis reflected that there were significant positive correlations between the mean numbers of the insect population with LA and TDR. Plants that received more water produced more growth and height with small number of insect population with negative correlations. Previous research found that more sticky honeydew sugars reduced whitefly population on non-water-stressed cotton plants compared with the water stressed cotton. Also several studies found that whitefly host prefers water-stressed cotton plants.  Results in this study indicated that treatment one (daily watering) was severely affected by the drought impact.