Police who tasered an 87-year-old grandmother while she was collecting dandelions say they did so "rather than using deadly force".

A worker at the Murray County Boys & Girls Club in Chatsworth, Georgia called 911 after seeing Martha al Bishara, who does not speak English, using a knife to cut the flowers in the club's grounds near her home.

Ms al Bishara, who is originally from Syria and speaks only Arabic, needed the dandelions to prepare a salad for her 71-year-old husband.

When officers arrived with guns drawn, they struggled to make themselves clear.

"We began trying to communicate with her, telling her of course to drop the knife," said Chatsworth police chief Josh Etheridge.

"We didn't know if she just didn't understand us or was having some type of issue."

Police say they dropped their own knives on the ground to signal what they wanted Ms al Bishara to do.

Mr Etheridge said the use of a taser was justified, adding: "An 87-year-old woman with a knife still has the ability to hurt an officer."

He said the taser was deployed "rather than using deadly force to stop the situation".

Ms al Bishara was put in handcuffs and arrested.

Her granddaughter, Martha Douhne, said she "obviously did not look violent".

The pensioner has been having trouble sleeping since being tasered and is scared to go outside.

"She thought she got shot," Ms Douhne told NBC.

"We have never really told her about stun guns or Tasers, and so she doesn't know what that is."

The officer who tasered her remains on duty, and the force is reviewing the situation, Mr Etheridge said.