Federico Medina Ravell was not at home at the time but Chavez supporters said officers confiscated several computers, Britain's The Guardian reported.
Medina is the cousin of Alberto Federico Ravell, a well-known opposition journalist and co-founder of Globovision, a major news broadcaster and staunch critic of the Chavez government.
He is suspected of instigating terrorism through social networking sites and is believed to be behind a Twitter account that claims Chavez will not return from Cuba where he is recuperating from cancer surgery.
"We have to confront this impressive power on social networks that is able to destroy the consciousness of a people with ill-intentioned and misconstrued news," said Piedad Cordoba, a long-time Chavez ally.
Analysts on the state-backed channel Telesur charge the government is under information attack.