The existence of the critical point (CP) of strongly interacting matter is still an open problem. An extensive strong interactions program including a search of the CP and the study of the onset of deconfinement was started by the NA61/SHINE experiment at the CERN SPS. A two dimensional scan of the phase diagram is performed to search for the CP and to shed light on the phase transition region. This program includes studies of hadron production in proton- proton, proton-nucleus and nucleus-nucleus interactions measured in a wide range of colliding energy and system size. Correlations between various observables measured at midrapidity as well as in separated rapidity intervals are considered as additional and sensitive tools of this phase diagram scan. We present NA61/SHINE results of studies of energy dependence of two- particle correlations of pseudo-rapidity and azimuthal angle in p+p collisions at the SPS and the first results on correlations between multiplicity and mean transverse momentum in 7Be + 9Be