We present an analysis of the sensitivity of LHC searches for new spin-0 particles produced via gluon-fusion and decaying into top-antitop-quark (tt¯) final states to generic axion-like particles (ALPs) coupled to top-quarks and gluons. We derive new limits on the effective ALP Lagrangian in the linear representation in terms of the Wilson coefficients ct and cG̃ based on the existing CMS search using 35 fb−1 of proton-proton scattering data collected at √s = 13 TeV. We further investigate posssible distinctions between ALPs and pseudoscalar Higgs bosons as predicted by the Two Higgs doublet model (2HDM), and find that a distinction is possible with data anticipated to be collected during the high-luminosity phase of the LHC for a significant range of the effective ALP-gluon coupling.