Galactic massive lenses with large Einstein Radius should cause a measurable astrometric microlensing effect, i.e. the light centroid shift due to motion of two images. Such shift in the position of a background star due to microlensing was not included in the Gaia astrometric model, therefore significant deviation should cause Gaia astrometric parameters to be determined incorrectly. Here we studied the photometric microlensing events reported by the Gaia mission in DR3 and selected those with potential astrometric signal. We identified one event, GaiaDR3-ULENS-001, for which Gaia poor goodness of fit and erroneous parallax could indicate presence of the astrometric signal. Base on the photometric microlensing model, we simulate Gaia astrometric time-series with astrometric microlensing effect. We find that adding microlensing with Einstein Radius of 1.5, reproduces well the astrometric quantities reported by Gaia. We estimate the mass of the lens to about 0.6 sun masses and its distance, proposing the lens is a nearby isolated white dwarf.