The assault on the town of Mpeketoni late on Sunday and a nearby village the following night left at least 60 dead, were claimed by Somalia's Islamist Shebab but blamed by the president on local political networks.
"We have arrested several suspects in connection to Mpeketoni incident including the owner and driver of one the vehicles used by attackers," police chief David Kimaiyo said.
"More suspects including leaders are being interrogated."
Despite an immediate claim of responsibility for the latest carnage from the Al-Qaeda-linked Shebab, Kenyan President Uhuru Kenyatta instead blamed "local political networks" along with an "opportunist network of other criminal gangs".
Also being held by police is "a suspect who was operating social media accounts purportedly used by Al-Shebab to claim responsibility," he said.
The Shebab gave a statement to AFP via telephone claiming responsibility for the attacks.