In a post on the Lee Rigby Foundation Facebook page, Lyn Rigby said her family were “aware of a number of posts using images of Lee and his murder in a divisive way”.
She said: “Lee proudly served his country to protect the rights and freedoms of all members of this great melting pot of a nation.
“Seeing his image used to cause hate of any kind, especially for those exercising their freedoms in protest against this issue, hurts.
“We find these posts extremely heartbreaking and distressing, and in complete opposition to what Lee stood for.”
Private Lee Rigby, 25, of the Royal Fusiliers, was attacked by two Islamic extremists in May 2013 as he walked off-duty near the Royal Artillery Barracks in Woolwich, south London.
His killers, Michael Adebolajo and Michael Adebowale, are both serving life sentences.
This week detractors of the Black Lives Matter movement have posted details of Private Rigby’s murder on social media alongside criticism of recent protests sparked by the death of George Floyd in Minneapolis.
The 46-year-old African American died on May 25 after white police officer Derek Chauvin knelt on his neck for almost nine minutes during an arrest, as Mr Floyd gasped “I can’t breathe”.
Thousands of anti-racism demonstrators gathered in Hyde Park yesterday in response to Mr Floyd’s death, while the US has been rocked by the largest wave of civil unrest since the assassination of Martin Luther King Jnr in 1968.
Mrs Rigby wrote: “We ask you all to please stop using his image and memory in such posts as he was a lover of all of humanity. Every race, gender, creed, sexuality and colour. “So seeing such use of his name harms not only his family but his legacy and memory.
“Our thoughts and support goes out to George Floyd’s friends and family at this tragic time.”