The video-sharing website has been blocked in Pakistan since September 2012 over its hosting of the "Innocence of Muslims" movie that sparked furious protests around the world.
The Supreme Court ruled at the time that the site should be banned until a way was found to block all so-called blasphemous content.
"(The) matter was reviewed several times but the situation effectively remains the same," the minister for information technology and telecommunication Anusha Rehman told the Senate Friday.
"The government does not want to take any chance and wants to make sure that after the unblocking YouTube, no offensive content remains viewable in Pakistan," a senior government official told AFP.
"So far no tool or solution has been found which can totally block offensive content, that is why YouTube remains blocked and it will remain so indefinitely," the official said.
Blasphemy is a contentious issue in Pakistan and the country has seen violent riots sparked by content deemed offensive to Islam, including the "survivors" edition of French satirical magazine Charlie Hebdo that had a cartoon of the Prophet Mohammed on its front cover.
Free speech campaigners in Pakistan have long complained of creeping censorship in the name of protecting religion or preventing obscenity, and have described the ban on YouTube as a violation of civil rights.
In November 2011 the telecommunications authority tried to ban nearly 1,700 "obscene" words from text messages, which included innocuous terms such as "lotion", "athlete's foot" and "idiot".
In 2010 Pakistan shut down Facebook for nearly two weeks over its hosting of allegedly blasphemous pages. It continues to restrict thousands of online links.