The protesters were from Outside Agitators 206. They claimed to speak in the name of BLM, but their primary web presence is here:
Outside Agitators 206
Among the few links on their page I found this one:
Black Agenda Report
This is the website of a man named Glen Ford. In the linked article, he states the need for black people to "declare war on the Democratic Party ...
To succeed, the Black Lives Matter Movement must transform the politics of Black America. By definition, that means declaring war on the Democratic Party, and forcing Black politicians and activists to choose between the Party and the people’s struggle. The Democrats understand the logic, and have mounted a systematic cooption-repression response that will intensify as the election season – and Black cities – heat up.
As usual, the Democrats will try to make Black people more angry at the terminally racist Republican Party than at the police and local administration of their (typically) Democrat-run city. Hillary Clinton is already making noises of empathy with Blacks suffering under the urban police state. However, the Black Lives Matter movement has no institutional stake in the victory of either party, but is, in fact, locked in mortal political struggle with other Black people in the Democratic Party. These Black Democrats will insist on a truce, a cessation of agitation against national or local Democrats, until after the election. As with the Occupy movement, this will be accompanied by intensified police pressures against activists. At the end of the process, the Black Lives Matter movement is meant to go the way of Occupy, lost in the electoral Mardis Gras – killed by Democrats, not Republicans.
So no, there is no confusion, they have no intention of going after the Republicans. The Democrats are their enemy.