The 25-year-old pop star sang the Franklin's classic "(You Make Me Feel Like) A Natural Woman," one of a series of tributes by musicians to America's "Queen of Soul" at her marathon funeral attended by presidents, stars and music royalty.
After her performance, she was congratulated by Bishop Charles H. Ellis III, who wrapped his arm around her, his hand high above her waist and his fingers pressed against her chest.
"It would never be my intention to touch any woman's breast. ... I don't know, I guess I put my arm around her," Ellis said in comments to US media confirmed to AFP on Saturday.
"Maybe I crossed the border, maybe I was too friendly or familiar, but again, I apologize."
The moment drew fierce criticism online.
"I'm really sorry you had to go thru that @ArianaGrande that groping was beyond blatant and we could all see and feel your discomfort," wrote television host Claudia Jordan.
Ellis also apologised for a joke he made to Grande about her name: "When I saw Ariana Grande on the program, I thought that was a new something at Taco Bell," he said, referring to a popular Mexican fast-food chain.
"I personally and sincerely apologize to Ariana and to her fans and to the whole Hispanic community," Ellis said.
Grande is of Italian descent.
This article first appeared on EWN : Aretha Franklin funeral bishop apologises for 'groping' Grande