Criticising the arrests of two young women for posting anti-Sena remarks, the Communist Party of India-Marxist sought action against police officers who slapped cases against them.
"The Congress-NCP state government must take immediate action and stop pandering to the whims and fancies of the Shiv Sena, as it has often done in the past," a CPI-M statement said.
A statement released by the CPI-M's Maharashtra unit said the Marxists had always opposed "the violent culture of regional chauvinism practiced by the Shiv Sena" and now also by the Maharashtra Navnirman Sena (MNS).
It said the Shiv Sena ideology was deeply communal and reminded that the late Bal Thackeray hailed the demolition of the Babri Masjid.
"The Shiv Sena was deeply complicit in the Mumbai riots and the violence against Muslims after the Babri demolition."
"Thirdly, the Shiv Sena's politics was deeply anti-working class and anti-Communist, and in this it received the full and consistent support of successive Congress governments and of the big capitalists of Mumbai."
Accusing the Shiv Sena of being "deeply anti-Dalit", it pointed out the physical attacks by Shiv Sainiks on the Dalit Panthers in the early 1970s led to the death of Panther activist Bhagwat Jadhav.
"Finally, there was the Shiv Sena's opposition to democracy and support of dictatorship.
"This was made amply evident by Thackeray's support to the Emergency; his open glorification of Hitler; and the Shiv Sena attacks on journalists, cultural and literary figures and others who dared to be critical."
It said it was this intolerance which led to the "arbitrary arrests of two young girls in Palghar and the attacks on the hospital of the uncle of one of them".
The women were arrested because they opposed on Facebook the shutdown that followed Thackeray's death Saturday.
The CPI-M demanded that the cases against them be dropped and sought "strict action" against the police officers who instituted these cases and also against the goons who attacked the hospital.
"The CPI-M has always, and will in the future, continue to fight the chauvinist, communal, casteist and anti-working class policies of the Shiv Sena."