The TMC activists raised slogans and staged a march at Jantar Mantar. Roy told reporters that yesterday's incident was "shameful" for democracy, and condemned the attack.
"The manner in which Mamata Banerjee was physically manhandled, the manner in which Amit Mitra was assaulted is a shameful affair for democracy. It's the culture and creed of the CPI-M. In the last 35 years, 55,000 Trinamool Congress and Congress workers were killed by the CPI-M," Roy claimed.
"They (CPI-M) were thrown out by the people of Bengal but still they are not changing their attitude. They are doing this sort of activities, we are condemning it."
Protesters from CPI-M and SFI ambushed Banerjee and other ministers, including Mitra, when they arrived at the Planing Commission complex for annual state plan discussion yesterday.
While the Chief Minister was shielded by policemen, it was left to Mitra to face the anger of the activists who were protesting the death of SFI member Sudipto Gupta in police custody in Kolkata last week.
The 65-year-old Finance Minister was pushed and jostled around as he tried to enter the Yojna Bhawan building. A woman protester thumped him twice on his chest and his kurta was torn in the melee.