The National Directorate of Security (NDS) said the three militants were arrested were assigned by Taliban group leader Mullah Nemat to carry out the assassination of the officials, elders and religious clerics.
A statement by NDS said the militants were planning to carry out the assassinations in Nad-e-Ali district before they were arrested by the security forces.
The intelligence operatives confiscated a pistol with a silencer and 10 hand grenades from the detained militants, NDS said.
NDS said numerous assassination attempts against the local officials, elders and religious clerics were foiled with the arrest of the three militants assigned for the task.
The Taliban militants group has not commented regarding the report so far.
Helmand is among the volatile provinces in southern Afghanistan where anti-government armed militant groups are actively operating and frequently carry out insurgency activities.