We have studied the small-deformation rheology of a (semi-) two-dimensional model network of spherical particles, representing an adsorbed monolayer of protein at a fluid-fluid interface. The particles are confined at the interface in a steep potential A percolating network is generated through the of flexible but irreversible bonds between the particles. The shear rheology behavior of this system is similar to that of its three-dimensional counterpart, although the stress time correlation function does decay more slowly for the interfacial system. At not too high particle concentrations the dilatational rheology is completely dominated by the interactions due to the bonds between the particles. When the interface is compressed or expanded in one direction, the stress response is strongly orientation dependent. At high particle concentrations a compression of the interfacial film is very similar to a compression of a hard sphere system at the same concentration.