Saldanha, 46, was found hanged last December in her hospital lodgings in London, days after she answered the hoax call from DJs Mel Greig and Michael Christian at Australian radio station 2Day FM.
As part of the ruse, the pair had pretended to be Queen Elizabeth and William's father - heir to the throne Prince Charles.
Saldanha put the call through to a colleague who, despite the DJs unconvincing accents, disclosed details of the Duchess of Cambridge's condition during treatment for an extreme form of morning sickness in the early stages of pregnancy.
The story was reported across the globe and Saldanha's subsequent death provoked widespread anger.
British Prime Minister David Cameron called it a tragedy and police launched an investigation to see if any offences had been committed.
"We have concluded that there is no evidence to support a charge of manslaughter," said Malcolm McHaffie deputy head of special crime at Britain's Crown Prosecution Service.
Other possible charges under the Data Protection Act, the Malicious Communications Act and the Communications Act would also not be in the public interest he said, adding it was not possible to extradite individuals from Australia over offences these laws covered.
"However misguided, the telephone call was intended as a harmless prank," he said.
British police at the start of an inquest in the death said three notes had been discovered with Saldanha's body.
Media reported that one blamed the DJs while another criticised staff at London's King Edward VII hospital.
Greig and Christian, who were both suspended, appeared on Australian television in the aftermath to apologise for their actions and to say Saldanha's death had left them heartbroken.
2DayFM this week officially cancelled their show, which had been off the air since the incident, but said the DJs had not been sacked and were expected back on air although no date for their return was given.
Australia's media regulator has launched an investigation to see whether the radio station breached its licence conditions and commercial radio codes of practice.
Southern Cross Austereo, parent company of the radio station, has also apologised and promised to donate advertising revenue to a fund for Saldanha's family with a minimum contribution of A$500 000 ($525 000).