Evidence showed there was "no explosion" behind the deadly crash last Friday of SpaceShipTwo, he told Sky News television.
"I've never seen such irresponsible innuendo and damaging innuendo," the tycoon said.
Branson also vowed to "push on" with Virgin's passenger travel space programme once the reasons behind the accident, in which one test pilot died, had been worked out and corrected.
Branson stressed that the US National Transportation Safety Board investigating the crash had found that the spacecraft's fuel tanks and engine found in the Mojave Desert in California were not broken apart.
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The crash of SpaceShipTwo is a major setback to Branson's ambition to start ferrying wealthy customers to the edge of space, charging USD 250,000 (200,000 euros) per ticket.
But the serial entrepreneur made clear he was unbowed in his ambition.
"We must push on," he said. He adding though: "We will not fly members of the public unless we can fly myself and family members."
The investigation into the crash is ongoing and is not expected to conclude for another year.