Wataraka Vijitha Thero was found tied up and wounded on Friday and arrested on his discharge from hospital.
Police accuse him of changing his account of what happened and allege he injured himself.
The monk is a vocal critic of the hard-line Sinhalese Buddhist Brigade,
whose rally in a southern town triggered deadly anti-Muslim riots this
month.
Four people were killed in the violence which came after a rally by
firebrand monk Gnanasara Thero who leads the Buddhist Brigade (BBS).
The BBC’s Charles Haviland in Colombo says Wataraka Vijitha Thero had
become a voice of reconciliation at a time when extremist monks are
inciting racial hatred.
On being discharged from hospital he was arrested and brought before a judge who remanded him in custody for a week.
The monk, who has shared a platform with Muslim and other minority
leaders, says he has been subjected to character assassination and
jailed while an extremist monk remains free.
In the past few days there have been further sporadic attacks on Muslim
homes, businesses and mosques around the country, our correspondent
says.