  We model the soft pomeron in QCD using a scalar Polyakov string with
extrinsic curvature in the bottom-up approach of holographic QCD. The overall
dipole-dipole scattering amplitude in the soft pomeron kinematics is shown to
be sensitive to the extrinsic curvature of the string for finite momentum
transfer. The characteristics of the diffractive peak in the differential
elastic $pp$ scattering are affected by a small extrinsic curvature of the
string.
