Informing people and encouraging them to stand in solidarity with groups at risk of discrimination "needs to be addressed", she said.
People take part in a protest for the killing of Alton Sterling and Philando Castile during a march along Manhattan's streets in New York July 7, 2016.
Black Lives Matter began in 2013 after black teenager Trayvon Martin was shot to death in Florida by one-time community watch volunteer George Zimmerman, who was later acquitted.
Whether President Barack Obama, his Department of Justice, and the mainstream media are held to account for their roles in crafting false narratives and ginning up anti-police hate since the justified self-defense shooting of Michael Brown and the deaths of a dozen other violent minority criminals remains to be seen.
Members of the local black community gathered for a peaceful vigil in the South End on Friday night to mourn black Americans who were fatally shot by police this week in Louisiana and Minnesota and to discuss ways to move forward.
"We know segments of our society are disproportionately marginalized by institutional structures", said Nav Kaur, a rally organizer.
The marches have been organised by the Black Lives London Matter Movement who, via their Twitter account, say it's a "plea, a cry for help".
Mark Wilson Getty Images
In Philadelphia, Erica Mines of the Philly Coalition for REAL Justice said the group is planning a "Weekend of Rage".
"You don't think it hurts waking up every morning seeing those with the same skin colour as us on the news murdered in cold blood?" In her narration, she says Castile informed the officer that he was licensed to carry a firearm.
Indeed, as the ACLU of Texas said in its response to the shootings, "If the night had gone as the protesters and police planned, this would have been a demonstration of what makes our country great: a citizenry publicly proclaiming their objection to government wrongs, and public officials protecting the citizenry's constitutional right to air their anger and disapproval".
Police killed one suspect, a 25-year-old former Army reservist, and arrested several others.
Jim Pasco, executive director of the National Fraternal Order of Police, said heightened media attention and the ubiquity of cell phones have fuelled recent firings and resignations. Dress in black, the event organizers said, and feel free to bring posters and signs. "The suspect stated he wanted to kill white people, especially white officers", Brown said.
The two incidents appear to be police overreacting because neither man appeared to be threatening them.
"Black Lives Matter in Cuyahoga County condemns the killing of innocent police officers by rouge citizens as much as we condemn the killing of innocent black men, women and children by rogue police officers", the group posted on its Facebook page.