All 300,000 mosques in Bangladesh have been asked give a sermon against terrorism and extremism in their Friday prayers this week.
The sermon, written by the state-run Islamic Foundation, condemns the "unjust killing of any human being".
It also urges parents to protect their children from "brainwashing".
The move comes after two deadly Islamist attacks in Bangladesh in recent weeks, including a siege on a Dhaka cafe that left 20 people dead.
That attack, and an attack on police guarding the country's largest Eid gathering in Kishoreganj, were both claimed by the Islamic State militant group.
'No place for terror'
The sermon said: "The Prophet says the greatest of all sins is to kill a human being. No distinction between Muslim or non-Muslim has been made here."
The foundation said it hoped imams would use the message, or take inspiration from it.
The imam of the national mosque, Mohiuddin Quashem, read out the message in his Friday sermon.
He told the BBC's Akbar Hossain: "I said no human being can kill another human being. Islam never supports this."
The move is seen as part of the government's efforts to monitor activities in mosques, following concerns about radicalisation.
Abdullah Hasan, who joined the prayer at the national mosque, told the BBC: "I support the government's move to have an identical khutba [prayer]. The imams should deliver this sermon to fight against militancy in the name of Islam."
However, another worshipper, Muniruzzamn, argued that it was excessive regulation. "The imams should have their freedom, they should choose what they will speak about. It looks like government-controlled khutba. I don't think it will help."
Bangladesh has seen a spate of attacks on secular bloggers, gay activists, academics and members of religious minorities, with more than 40 killed since February 2013.
Many of those attacks were claimed by Islamic State militants or al-Qaeda affiliates, although the government has blamed local groups and the opposition instead. The opposition denies the claims.