The police said that the six were ordered to be remanded till April 2 when an identification parade would be held.
The mob attack on the clothing store Fashion Bug owned by Muslims damaged property.
Bodu Bala Sena, the Buddhist nationalist group, is allegdly leading a campaign which they say targets the growing Muslim extremism in the country.
Less than 10 per cent of Sri Lanka's population of 20 million are Muslim. The majority are Sinhalese Buddhist, while most Tamils are Hindu.