Tuesday's attack in the Sagaing area was the deadliest in a recent string of military air attacks, with children reported to be among the dead, and has drawn global condemnation.
Myanmar has been in chaos since a military coup in early 2021 that upended a decade of tentative democratic reform, with a bloody crackdown on protests giving rise to an armed struggle against the junta.
"All forms of violence must end immediately, particularly the use of force against civilians," chair Indonesia said in a statement.
"This would be the only way to create a conducive environment for an inclusive national dialogue to find a sustainable peaceful solution in Myanmar," it said.
ASEAN agreed a peace plan with the junta in 2021 but members have been increasingly frustrated by the military's failure to halt offensives and open dialogue with the resistance movement backed by ethnic minority armies and a shadow National Unity Government (NUG), which the junta has declared a "terrorist" movement.
A junta spokesperson said Tuesday's attack targeted a ceremony held by the NUG for their armed People's Defense Force, adding the attack aimed to restore peace and stability in the region.