  In this paper, we present a new method to search for a short, a few tens of
milliseconds long, postmerger gravitational-wave signal following the merger of
two neutron stars. Such a signal could follow the event GW170817 observed by
LIGO and Virgo detectors. Our method is based on a matched filtering statistic
and an approximate template of the postmerger signal in the form of a damped
sinusoid. We test and validate our method using postmerger numerical
simulations from the CoRe database. We find no evidence of the short postmerger
signal in the LIGO data following the GW170817 event and we obtain upper
limits. For short postmerger signals investigated, our best upper limit on the
root sum square of the gravitational-wave strain emitted from 1.15 kHz to 4 kHz
is $h_{\text{rss}}^{50\%}=1.8\times 10^{-22}/\sqrt{\text{Hz}}$ at 50% detection
efficiency. The distance corresponding to this best upper limit is 4.64 Mpc.
