"You do not have the right to execute someone for shoplifting," Supervisor Shamann Walton said at Tuesday's board meeting.
Supervisor Aaron Peskin said, "At a minimum, this appears to be a manslaughter case to this non-attorney."
Peskin said he plans to formally draft a resolution asking Jenkins to reconsider.
The guard, Michael Earl-Wayne Anthony, 33, was released from jail, days after police say he shot and killed Banko Brown, 24, at the store at Fourth and Market streets.
"I am deeply concerned based on my conversations with law enforcement by the district attorney’s decision not to charge at least manslaughter," Peskin said.
Jenkins said video evidence and statements made by the guard and witnesses indicate the guard acted in self-defense after Brown threatened him at the store.
"This was a very, very difficult decision to have to make," Jenkins said. "You never want to have to tell a family that's wanting justice that, you know, the outcome of the case isn't going to go in the direction that they hoped."
Speakers at the board meeting Tuesday blasted Jenkins.
"A life was tooken– at Walgreens," one woman said. "The fact that that DA does not want to press charges for what happened to a young, black trans youth is totally unfair."
Another woman agreed, saying, "That armed guard was scared for his life - when he had the weapon? When he took a life?"
KTVU legal analyst Michael Cardoza said Peskin and others should not be wading into legal affairs.
"Why are we politicizing this?" Cardoza said. "District attorney made a decision, legislators should stay out of it."
Cardoza said under the law, manslaughter is not a viable alternative to murder if the DA says the guard shot Brown to protect himself.
"Self-defense is self-defense," Cardoza said. "In this case, the politicians seem to be getting involved to garner votes to assuage their constituents."
Henry Lee is a KTVU crime reporter. E-mail Henry at Henry.Lee@fox.com and follow him on Twitter @henrykleeKTVU and facebook.com/henrykleefan