CCTV footage released by the police showed a hood-up man grabbing an elderly woman’s handbag and trying to escape.
"I walked with my friends, they dared me... whether I can take away (the bag) or not. I pulled it, the woman fell off the curb," said the 22-year-old detainee, who has not been named.
"I tried to pull my hand out, dragging her across the ground. When I freed my hand, I ran away, I did not take anything, just ran away," he added.
The woman, who is said to be 70 years old, clutched onto her belongings making the attacker drag her along the street for several feet, the video showed.
After a brief fight over the bag, the robber gave up and ran away as a bystander interfered.
The attacker was arrested shortly after by police officers, the interior ministry said in a statement.
Moscow police said the suspect, who claims he later came back to the scene with a whiskey bottle to apologize, faces criminal charges of attempted robbery.