Chandy, who arrived in the state capital in the wee hours, is undergoing treatment at the Medical College Hospital for the forehead injury and swelling on the chest, hit by a stone during the incident in Kannur.
Doctors attending on 70-year-old Chandy said his condition was stable but advised complete rest for three days compelling him to cancel all engagements, including the mass contact programme at Kollam on Tuesday.
In an overnight search, police rounded up 22 CPI-M workers from different parts of Kannur and arrested 17 of them, who were remanded. They had been charged with the Indian Penal Code 307 (attempt to murder), 324 (voluntarily causing hurt by dangerous weapons or means) and other sections including unlawful assembly.
The police also registered cases against a large number of CPI-M leaders, including MLAs from the district K K Naryanan and C Krishnan.
State Home Minister Thiruvanchur Radhakrishnan said the incident during a LDF protest was a "planned attack" and wanted the CPI-M to leadership to call off their agitation over the solar scam.
"What happened yesterday was a planned attack as the LDF volunteers have been blocking the chief minister's engagement across the state for the last five months,” the minister told reporters.
CPI-M state secretary Pinarayi Vijayan vehemently denied the involvement of LDF workers in the attack and dared the government to conduct a thorough investigation to track down the real culprits instead of haunting the CPI-M activists.
Chandy had a steady stream of visitors including Governor Nikhil Kumar, CPI-M stalwart and opposition leader V S Achuthanandan and ministers and Congress leaders.
President Pranab Mukherjee and Prime Minister Manmohan Singh called Chandy over phone and enquired about his health, official sources said.
The ongoing campaign by CPI-M-led LDF over the solar panel scam turned violent on Sunday as protesters allegedly pelted stones at Chandy at Kannur, where he had gone to attend a couple of engagements including the valedictory of the state police athletic meet.
In view of the incident, the state government has proposed to provide "Z" category security to Chandy.
How will Chandy fight the solar scam's eclipse on Kerala?
Solar scam rocks Kerala, CM Chandy say he won't quit
Chandy discusses Kerala politics with Rahul
Solar scam: Chandy's son sends legal notice to BJP leader