During a telephonic conversation with Kerala Chief Minister Pinarayi Vijayan, Singh discussed with him the recent incidents of political violence in the state.
"I have expressed my concern over the law and order situation in the state of Kerala. Political violence is unacceptable in a democracy," he said in a tweet.
The home minister's phone call to the Kerala chief minister came a day after an RSS worker was hacked to death by a gang led by a history-sheeter near Thiruvananthapuram.
The home minister said he expects that the political violence in Kerala is curbed and the perpetrators are brought to justice expeditiously.
Police said 34-year-old Rajesh's left hand was chopped off in the attack which took place around 9 pm last night. An investigation has been launched and search is on for assailants, they said
BJP's Kerala unit president Kumanam Rajasekharan alleged the CPI-M was behind the attack, a charge denied by the district leadership of the left party.
The BJP has called for a state-wide hartal today.