We study the physical behavior of a five dimensional non-static spherically symmetric cosmological models in the presence of massive strings in the framework of $f(R,T)$ gravity proposed by Harko et al. (Phys. Rev. D 84:024020, 2011). Here $R$ is the Ricci scalar and $T$ is the trace of the stress energy tensor and the fifth dimension is not observed because it is compact. We solve the field equations (i) using a relation between the scale factors given by Samantha and Dhal (Int. J. Theor. Phys. 52:1334, 2013) and (ii) equations of state for string models. The models obtained correspond to $p$ -string, geometric string and massive string models in this modified theory in five dimensions. Cosmological parameters of the models are determined and their dynamical properties are discussed.