Convicted IRA terrorist Brian Kenna is chairman of Saoradh, the political wing of the New IRA, who shot dead Lyra in cold blood four months ago.
In an interview with Sky News, Mr Kenna said the continuation of violence was “inevitable” but Miss McKee’s death was “regrettable”.
Detectives believe the New IRA dissident for shooting dead the talented 29-year-old writer while she observed disturbances in Creggan on Thursday, April 18.
Lyra’s partner Sara Canning said: “Absolutely appalling statement by Brian Kenna.”
She added: “The police being in Creggan didn’t murder Lyra, the New IRA idiots did.”
The violence which led to Miss McKee being shot in the head by a member of the New IRA began after police conducted a search in Creggan estate ahead of the anniversary of the Easter Rising.
Miss Canning said: “They proved the police’s reason for being there by bringing a gun onto the streets and putting lives in danger, and ultimately murdering the love of my life.
“Had no gun come out they could have claimed unfair oppression, instead they totally justified the police presence.”
She said many more lives were also put in danger.
“It was not an accident, it wasn’t just regrettable, it was despicable.
“The blatant disregard for the people of the town and beyond is staggering.
“No lives should have been lost that night.
“There is no justification for murder.”Mr Kenna has denied any overlap between the leadership of his party and the New IRA but refused to condemn violence.
He told Sky: “The death of Lyra McKee was a very tragic event.
“It genuinely came about because of the heavy presence of the Police Service of Northern Ireland, flooding into Derry at seven o’clock in the evening, into parts of the Creggan.”
He added: “It was shocking and tragic and we’re on record as saying that we regret that death very, very much.”
The New IRA also detonated a car bomb outside Derry courthouse in January this year.