  The H.E.S.S. array of Cherenkov telescopes has performed, from 2004 to 2007,
a survey of the inner Galactic plane at photon energies above 100 GeV. About
400 hours of data have been accumulated in the region between -30 and +60
degrees in Galactic longitude, and between -3 and +3 degrees in Galactic
latitude. Assuming that dark matter is composed of Weakly Interacting Massive
Particles, we calculate here the H.E.S.S. sensitivity map for dark matter
annihilations, and derive the first experimental constraints on the
''mini-spikes'' scenario, in which a gamma-ray signal arises from dark matter
annihilation around Intermediate Mass Black Holes. The data exclude the
proposed scenario at a 90% confidence level for dark matter particles with
velocity-weighted annihilation cross section sigma v above 10^28 cm3s^-1 and
mass between 800 GeV and 10 TeV.
