Dissident republicans behind rioting that led to the murder of a journalist in Londonderry should "cease their activities", the Sinn Féin leader has said.
Lyra McKee, 29, was shot on Thursday night as she observed the violence.
At an Easter Rising commemoration in Belfast on Sunday, Mary Lou McDonald said there was "no support" for armed action.
"There is no justification for armed actions," she said.
"It is past time for these groups that masquerade as republicans to pack up."
Earlier on Sunday, Derry's Catholic bishop Donal McKeown said the nationalist Creggan community, where Ms McKee died, needed "liberation" from dissident republicans.
He told the BBC's Sunday Sequence that people in the Creggan estate were "disgusted at what happened".
Speaking at Milltown Cemetery, Ms McDonald said no cause was "progressed by armed actions".
She said the people of Derry and beyond had echoed this sentiment "with one voice" following Ms McKee's "brutal killing".
Ms McDonald also told the crowd that Northern Ireland's current political "stalemate cannot continue".
In the absence of the power-sharing institutions, she said a new British-Irish partnership was needed to implement agreements and safeguard rights.