The ruling is the latest setback in the retired army general's attempt at a political comeback, The New York Times reported.
Musharraf already was under house arrest at his Islamabad-area villa in a separate case related to the emergency rule he imposed in 2007, when he detained and fired senior judges, the newspaper said.
Musharraf appeared in court in Rawalpindi Friday to hear charges related to the December 2007 assassination of the former prime minister and one-time political rival.
He was ordered to return to court Tuesday, attorney Salman Safdar said.
Mark Siegel, a Washington lobbyist and a friend of Bhutto, testified for the prosecution that Musharraf threatened her over the phone before she returned to Pakistan to run for prime minister.
Zulfiqar Ali, special prosecutor for the Federal Investigation Agency, was quoted by local news outlets as saying prosecutors will question Musharraf about allegations he threatened Bhutto and failed to provide her with security when she returned to Pakistan.
"I would call this a political case, based on mala fide," Safdar told the Times, using the Latin phrase for "bad faith."
"This is a prosecution merely on the basis of suspicion. The prosecution does not have concrete, tangible evidence."