Plasma waves which propagate in a pair of parallel metallic carbon nanotubes are studied within the framework of the classical electrodynamics. Electronic excitations over the each nanotube surface are modeled by an infinitesimally thin layer of free-electron gas which is described by means of the linearized hydrodynamic theory. An explicit form of plasmons dispersion in terms of interaction between the bare plasmon modes of the individual surfaces of the nanotubes is presented in this Letter.