The court also imposed a fine of Rs 1.25 lakh on him.
Riyas Aboobacker was convicted by the NIA special court in Kochi.
The accused persons had conspired and established an ISIS module in India with the aim of radicalising and recruiting impressionable youth, said NIA officials.
Two IS members had detonated their explosive belts in the crowd which had gathered at the cemetery in the southeastern Iranian city of Kerman.
According to the police, one of the accused had made IEDs and later tested them at several places in Delhi, Rajasthan and Haldwani in Uttarakhand.
An engineer by profession, Shahnawaz was arrested Sunday night from an area in southeast Delhi by the Delhi Police's Special Cell and is currently being interrogated, an official said.
NIA also revealed that the gang had also conspired to rob two major temples in central Kerala.
According to the police, these suspects were active members of the IS module with plans to abscond and officially join the terror group.
'Screening the movie would not disrupt communal harmony; a society as secular as Kerala will accept the film for what it is,' says court.
A bench headed by Chief Justice DY Chandarchud said the Central Board of Film Certification has already certified the film, which is slated for release on May 5.