Outside the hotel where Texas Republicans were staying, about two dozen protesters calling themselves employees of "Hallibacon" chanted: "We love money. We love war. We love Cheney even more." They accused Cheney and the company he once led of profiting from the war in Iraq.
Fourteen people were detained near Wall Street for blocking morning traffic. Another six protesters were arrested for wearing masks in a Harlem subway station, authorities said.
More than 500 people have been arrested in convention-related protests since late last week.
Relations between Republican National Convention (search) protesters and the thousands of New York City officers assigned to police them turned ugly Monday when a march from the United Nations to Madison Square Garden ended with a violent confrontation. Earlier, smaller demonstrations had focused on health care, civil rights, homelessness and other areas in which protesters say Republicans have failed the country.
A protester attacked and seriously injured a plainclothes detective, according to police and witnesses. Hundreds of police in riot gear swarmed the area, pushing protesters away from the Garden and into nearby side streets. Four other police officers suffered minor injuries during the scuffle.
Police Commissioner Raymond Kelly called it "a blatant, vicious attack."
The plainclothes detective who was attacked, William Sample, was hospitalized Tuesday with serious facial trauma, but his injuries were not life threatening, police said. His assailant was being sought by police.
The protest began when a crowd of several thousand outside U.N. headquarters negotiated with police to march to Madison Square Garden despite not having a permit.
"They asked if they could march, and we said yes," police Assistant Deputy Commissioner Tom Doepfner said. "We try to be nice."
A wall of uniformed police on motor scooters blocked off half of Second Avenue as marchers trooped down city streets. Police steered the restless, unwieldy crowd through midtown Manhattan rush-hour traffic as cars backed up 10 blocks in places.
The march ended at the protest area south of the Garden. Witnesses said the confrontation began as police tried to use interlocking metal fences to contain the thousands of protesters. Some protesters began to push against the fences, witnesses said.
The New York Civil Liberties Union accused police of having raised tensions by not explaining to the crowd what they were doing with the barricades. Police said they were keeping open a lane for emergency vehicles.