Militia groups have no role to play in Iraq, Shia politician declared on Saturday, a day before parliament was expected to sit.
Sadr, a former militia leader himself, urged Iraqis to rally behind the national army, police and security forces.
"Today, there is no place for sectarianism or ethnic division, but a national majority government where Shias defend the rights of minorities, the Sunnis and Kurds," Al-Sadr .
"Today there is no place for militias, and everyone will support the army, police and security forces," he continued, also rallying against corruption and calling on all sects to get behind reform."
While a governing coalition is yet to be formed, the Sadrist movement will have the highest number of lawmakers in parliament, after it won 73 out of 329 seats in recent elections – almost double the second-place Progress Party's tally of 37.
Sadr, a former anti-US militia leader, has opposed all foreign interference in Iraq and repeatedly called for US troops withdrawal from his country.
saw poor levels of participation and underwent a painstaking result-verification process.
Some experts and politicians hope for a new government by March.