Pat Jasan, which is known for flogging drug users, said it was calling off the mission in mountainous Kachin state because local police and military said they could not provide protection.
On Thursday the group said its members were attacked by a mob wielding explosives and stones after it set out from the town of Waingmaw to try and destroy nearby fields against the wishes of local farmers.
At least 32 members, including women, were injured in the fray.
"We have cancelled our mission and our members are now coming back to town," Lum Hkawng, a senior Pat Jasan leader in Waingmaw, told AFP on Sunday.
He accused local authorities of failing to protect them.
"When our leaders met with government officials, police said they couldn't give security. Also the army said we would have to talk to the central government directly as they couldn't give security."
Myanmar is the world's second largest opium producer after Afghanistan, despite the government's repeated vows to eliminate the drug trade.
Production has boomed amid weak law enforcement in the northern war-torn frontier, where ethnic minority rebel groups seeking greater autonomy from the state have been battling the Myanmar army for decades.
It is believed that both ethnic militias and the Myanmar military have tapped the lucrative multi-billion dollar trade to finance their long-running wars.
Impoverished farmers in the remote region meanwhile say they have few ways other than poppy cultivation to make a living.
The sudden attack on Thursday morning followed a standoff lasting several days between the Pat Jasan marchers and police, who had blocked the group from entering surrounding poppy fields, citing concerns armed farmers were ready to hit back.
Local police have not responded to repeated requests to comment.
Pat Jasan, determined to end the scourge of heroin addiction that has devastated local communities, formed its loose network two years ago with the backing of the powerful Kachin Baptist Church.
Its members, who don camouflage vests and combat helmets on their missions, have used forceful methods, including beating drug users, to try to break addictions.
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