  The elastic scattering for $^6$Li+$^{64}$Ni system was measured in the
bombarding energy range of 13 MeV $\leq$ $E_{lab}$ $\leq$ 26 MeV. A
phenomenological optical model analysis was performed and the behaviour of the
surface strengths of the potential components with decreasing energy was
extracted. A further analysis of the measured angular distributions, along with
the existing data for $^6$Li+$^{58}$Ni, was performed with two different model
potentials - one with the folded potential normalized with a complex factor
(OMP1) and the other with a {\it hybrid} potential composed of a renormalized
folded real and a phenomenological imaginary (OMP2) potential components - were
used in the calculation. All the model potentials predict similar energy
dependent behaviour for the interaction potential around the barrier. The
observed energy dependence of the strengths of the real and imaginary
potentials corroborate with the dispersion relation prediction for both the
$^6$Li+$^{64}$Ni and $^6$Li+$^{58}$Ni systems. Though the evidence of breakup
is distinct in the energy variation of the potential strengths, close to the
barrier the variation is more in the line of conventional threshold anomaly.
Also the threshold behaviour of the interaction potential does not indicate any
distinct isotopic dependence.
