  The production mechanism of quarkonia states in hadronic collisions is still
to be understood by the scientific community. In high-multiplicity $p+p$
collisions, Underlying Event (UE) observables are of major interest. The
Multi-Parton Interactions (MPI) is a UE observable, where several interactions
occur at the partonic level in a single $p+p$ event. This leads to dependence
of particle production on event multiplicity. If the MPI occurs in a harder
scale, there will be a correlation between the yield of quarkonia and total
charged particle multiplicity. The ALICE experiment at the Large Hadron
Collider (LHC) in $p+p$ collisions at $\sqrt{s}$ = 7 and 13 TeV has observed an
approximate linear increase of relative $J/\psi$ yield
($\frac{dN_{J/\psi}/dy}{<dN_{J/\psi}/dy>}$) with relative charged particle
multiplicity density ($\frac{dN_{ch}/dy}{<dN_{ch}/dy>}$). In our present work
we have performed a comprehensive study of the production of charmonia as a
function of charged particle multiplicity in $p+p$ collisions at LHC energies
using pQCD-inspired multiparton interaction model, PYTHIA8 tune 4C, with and
without Color Reconnection (CR) scheme. A detail multiplicity and energy
dependent study is performed to understand the effects of MPI on $J/\psi$
production. The ratio of $\psi(2S)$ to $J/\psi$ is also studied as a function
of charged particle multiplicity at LHC energies.
