President Maithripala Sirisena made new appointments last week to the council he dissolved following his shock election victory in January over strongman Mahinda Rajapaksa, who had applied tight controls over media.
Sirisena lifted media restrictions, allowing journalists more space to criticise the government.
He also freed the state-run media, which until then promoted the ruling party, to allocate space for the opposition as well.
The president has not explained his latest move.
The Committee to Protect Journalists said in a statement yesterday that Sirisena's revival of the council calls into question his commitment to democratic reforms.
Anyone found guilty of such offenses could be sentenced to a maximum of two years in prison, a fine or both.
"This decision comes from a government that lifted Sri Lankans' hopes that their country was ready to make a genuine effort to move away from the hostile environment that has surrounded the media for years," said Bob Dietz, the group's Asia program coordinator.
Rajapaksa's tenure was a dangerous time for journalists with numerous killings, forced disappearances and assaults. No one has been prosecuted in relation to these cases.