The prank call was pre-recorded and vetted by lawyers before being broadcast to listeners in Sydney.
Police said there were no suspicious circumstances surrounding Ms Saldanha's death and it is believed she took her own life.
Mr Holleran said the prank call followed company procedure.
"We're satisfied that that procedure was met," he told reporters in Melbourne on Saturday.
"We're very confident that we haven't done anything illegal. What happened was incredibly tragic and we're deeply saddened and we're incredibly affected by that."
Mr Holleran said the presenters were deeply shocked and had been offered counselling.
"At this time we've agreed they not comment about the circumstances," he said.
The station and the hosts had decided the show would not return to air until further notice out of respect for the tragedy.
Austereo, the owner of 2Day FM, was committed to working with any authorities investigating the tragedy, he said.
"Our primary concern at this time is for the family of nurse Saldanha."
Mr Holleran said there was no straightforward answer about when the presenters would return.
"These people aren't machines, they're human beings," he said.
"We'll make sure their wellbeing is the priority for us."
Meanwhile, Beyondblue chairman Jeff Kennett called on Australians to support the radio hosts.
The broadcasting watchdog, the Australian Communications and Media Authority (ACMA) said it would talk to the station about the "facts and issues surrounding the prank call".
In May, ACMA warned 2Day FM it could lose its broadcasting licence for any repeat of offensive on-air comments, after morning show presenter Kyle Sandilands called a female journalist a "fat slag" and threatened to "hunt her down".
Meanwhile, a Facebook page condemning the the 2Day FM presenters has been set up, entitled "RIP Jacinta Saldanha. Shame upon those stupid Australian DJs", and hundreds of people have taken to Twitter to condemn Greig and Christian, although a minority are defending them.
News of Ms Saldanha's death was acknowledged by the royal family.
"The Duke and Duchess of Cambridge are deeply saddened to learn of the death of Jacintha Saldanha," a statement issued by St James's Palace said.
"Their Royal Highnesses were looked after so wonderfully well at all times by everybody at King Edward VII Hospital, and their thoughts and prayers are with Jacintha Saldanha's family, friends and colleagues at this very sad time."
Hospital chief executive John Lofthouse described Ms Saldanha, married with two children, as a "first-class nurse who cared diligently for hundreds of patients".
A spokeswoman for Prime Minister Julia Gillard described the incident as a "terrible tragedy".
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-AAP