Mr Sonowal held "inflammatory statements" by a section of political parties and the media responsible.
Assam Chief Minister Sarbananda Sonowal on Friday described the killing of five people in Tinsukia district as "an act of cowardice" and announced a compensation of Rs 5 lakh to the next of kin of each of the deceased and a government job for a family member.
Mr Sonowal held "inflammatory statements" by a section of political parties and the media responsible for the attack that took place on Thursday night.
He appealed to the people to maintain peace and communal harmony in the state and promised stern action against the culprits.
Unidentified gunmen in battle fatigue shot dead five people, including three members of a family, beside a bridge near Kheronibari village after taking them there from their homes in the village.
"For this situation today, I hold responsible a section of political parties, organisations, news media, social media and people's representatives for their inflammatory statements," Mr Sonowal told reporters on the sidelines of a meeting.
He, however, did not identify any person or organisation.
"In the interest of the people, we will be forced to take strong action against inflammatory statements and hate speech by people's representatives, groups, parties or a section of media," the chief minister warned.
"All these have adversely affected the peaceful environment in the state. I want to warn these forces that the state government will take strong measures against them in the interest of the people of Assam," he said.
Police have been asked to arrest the culprits involved in the killings, Mr Sonowal said, adding that those seeking to pollute the peaceful environment of the state by making inflammatory statements would also be booked.
"The people want peace. I appeal all to maintain peace. We are all together. Nobody can destroy this age-old friendship, feeling of brotherhood and our understanding with each other," he said.
All the people of all the places of Assam - from Barak Valley to Brahmaputra Valley, from the hills to the plains - are safe, the chief minister said.
People from all communities across the state wanted the BJP-led alliance government to establish peace in the state and everyone wanted Assam to move forward in the path of development and progress, he said.
Meanwhile, Water Resources Minister Keshav Mahanta and Minister of State for Power Topon Kumar Gogoi, who visited the affected village, said Rs 5 lakh would be given to families of those killed and a government job would be provided to a family member of each of them.
The chief minister had sent Keshav Mahanta and Topon Kumar Gogoi to the village to take stock of the situation.