Trump also called the events after Khashoggi's death one of the "worst cover-ups".
He added: "They had a very bad original concept" and it was "carried out poorly."
Saudi Arabia has claimed that Khashoggi died accidentally in a brawl at the Saudi Consulate in Istanbul on October 2.
But Turkish officials say a 15-men team tortured, killed and dismembered the writer and say Saudi officials had planned the killing for days.
US Secretary of State Mike Pompeo says the Trump Administration is revoking the visas of some Saudi officials implicated in the death.
Global outrage
Meanwhile, facing global outrage over the killing of Jamal Khashoggi, Saudi officials are now admitting two key points - the latest twist in the kingdom's evolving efforts to explain Khashoggi's death.
They say that the journalist was targeted inside the kingdom's consulate in Turkey and a body double was on hand to aid in a cover-up.
This new version of events — which was described to AP by two Saudi officials — comes three weeks after the kingdom said Khashoggi left the consulate on his own and insisted that Turkish claims he was killed by an assassination squad were unfounded.
Now Saudi officials tell AP they did in fact send a team to Turkey that included a forensics expert and a member whose job was to dress in the 59-year-old writer's clothes and pretend to be him.
But they still insist that his death was an accident.
This account attempts to distance Crown Prince Mohammed bin Salman from the killing, even though officials linked to the 33-year-old ruler have been implicated.
But the fact that the Saudis are acknowledging some aspects of the account provided by Turkish authorities suggests that the kingdom is feeling intense global pressure, including from US President Donald Trump and members of Congress, some of whom have called for cutting off arms shipments and imposing sanctions.
There was no way to corroborate the Saudi account, which paints the suspects as rogue operators.
It also contradicts many observers who believe the complex scheme that led to Khashoggi's death could not have occurred without the knowledge of the crown prince, who controls all major levers of power in the kingdom with the blessing of his father, King Salman.
"It would have likely had the approval of the Saudi Government," said Robert Jordan, a former US ambassador to Saudi Arabia during President George W. Bush's Administration.
- AP