The paramedics and other rescue workers were shot dead on March 23 near the southern Gaza Strip city of Rafah and buried in a shallow grave where their bodies were found a week later by officials from the United Nations and the Palestinian Red Crescent.
A commanding officer is to be reprimanded and a deputy commander dismissed over the incident, the military said.
It did not say if anyone would face criminal charges.
"The examination identified several professional failures, breaches of orders and a failure to fully report the incident," the military said in a statement.
"The fire in the first two incidents resulted from an operational misunderstanding by the troops, who believed they faced a tangible threat from enemy forces. The third incident involved a breach of orders during a combat setting," it said.
A video recovered from the mobile phone of one of the dead men and published by the Palestinian Red Crescent showed uniformed emergency responders and clearly marked ambulances and fire trucks, with their lights on, being fired on by soldiers.
Red Crescent and UN officials have said 17 paramedics and emergency workers from the Red Crescent, the Civil Emergency service and the UN had been dispatched to respond to reports of injuries from Israeli air strikes.
The deaths of the 15 emergency responders sparked international condemnation.
Israeli authorities at first claimed that the medics' vehicles did not have emergency signals on when troops opened fire but later backtracked.
The military on Sunday said the deputy commander did not initially recognise the vehicles as ambulances due to "poor night visibility" and ordered troops to open fire on a group of individuals who emerged from a fire truck and ambulances.
The deputy commander perceived there to be a threat as an hour earlier troops had opened fire on another vehicle that they determined to belong to Hamas, the military said, but did not say how the soldiers had identified it as "Hamas vehicle".
Paramedic Munther Abed, one of the responders who was detained by the military and later released, has said soldiers opened fire on clearly marked emergency response vehicles.
The Red Cross said on April 13 another Palestinian emergency responder was being held by Israeli authorities.
The military has not commented on the claim.
The military has insisted that six of the 15 emergency responders killed were later identified as "Hamas terrorists".
Hamas has rejected the accusation.
About 15 minutes after the soldiers opened fire on the group of emergency responders, the military said that soldiers fired at a Palestinian UN vehicle.
The military blamed "operational errors in breach of regulation" for the incident.
"At dawn, it was decided to gather and cover the bodies to prevent further harm and clear the vehicles from the route in preparation for civilian evacuation," the military said, adding that removing the bodies was reasonable "under the circumstances" but that crushing the vehicles was "wrong".
"In general, there was no attempt to conceal the event, which was discussed with international organisations and the UN, including co-ordination for the removal of bodies," it said.
The military said that a commanding officer would be reprimanded for his "overall responsibility for the incident".
A deputy commander would be dismissed from his position due to being the field commander and for providing an "incomplete and inaccurate report" of the incident.
with AP and DPA
