President Nicolas Maduro said the officer was killed by a sniper and branded the protesters "murderous".
More than 240 people were arrested after the pre-dawn raids on four camps in the east of the capital.
Since anti-government protests began in February, more than 40 people have been killed, and thousands more arrested.
"A sniper killed the policeman while he was cleaning debris left by these violent, murderous protesters," a sombre Mr Maduro said during a televised address.
"He was vilely killed," he added.
Three other policemen were wounded, one by gunfire, Venezuelan media reported.
Interior Minister Miguel Rodriguez said police had found "drugs, weapons, explosives and mortars" in the camps.
The violence erupted after raids by members of the National Guard broke up four tent camps maintained by student activists.
Hundreds of demonstrators poured on to the streets and set up barricades. Masked youths threw stones and petrol bombs, while police responded with tear gas.
Witnesses said shots were fired from buildings into the streets, but this could not be confirmed.
Mr Rodriguez said 243 protesters had been detained and that the authorities were currently determining whom to charge.
He said protesters had used the camps as bases to launch "violent attacks", after which they would "hide... saying they were taking part in a peaceful protest".
Earlier this week, the pressure group Human Rights Watch accused Venezuelan security forces of illegally detaining and abusing protesters.
Demonstrations were triggered by frustration with Venezuela's high crime rates and poor economic situation but have grown into a wider anti-government movement.
Students have been at the forefront of the protests, erecting barricades and organising demonstrations and sit-ins.
The government has labelled the protesters "fascist agitators", accusing them of fomenting a coup against the left-wing government of President Maduro "with US backing".
A policeman has been shot dead in the Venezuelan capital Caracas after security forces broke up protest camps, officials say.