An improvised bomb destroyed two to three metres of the railway connecting Baramulla town in the north with Qazigund in the south, near Kakapora village about 40km south of Srinigar.
There were no casualties.
Earlier this week three Indian soldiers and five rebels were killed in two gunbattles.
The Indian army has warned violence in Kashmir is likely to rise in the summer and says 400 Islamic fighters are waiting to cross into Kashmir from Pakistan.
The violence comes a day after India blamed the Pakistan-based group Lashkar-e-Taiba for an attack that killed seven Indians in teh Afghan capital, Kabul, on 26 February.
Pakistan and India dispute control of the divided, Muslim-majority state. Separatist groups, some armed and some peaceful, have been campaigning either for independence or attachment to Pakistan for decades.