Speaking on Tuesday at the Oval Office, the United States leader said his Turkish counterpart had been "pretty rough" on Saudi Arabia when he addressed the writer's killing in parliament earlier in the day.
"They had a very bad original concept", the president responded. "I don't think that any country would dare do such a thing without USA backing", Iranian President Hassan Rouhani said, according to AFP. And they should be in big trouble.
On October 2, the day of the killing, operatives disabled CCTV cameras at the consulate, Mr Erdogan said.
He said the 15 "intelligence, security and forensic personnel" who flew to Istanbul just hours before the killing - returning home afterwards - should be sent back to face trial.
It was the first time a Turkish official has publicly accused Saudi officials on record of the premeditated killing of Khashoggi.
The Trump administration took its first concrete steps to penalize Saudi Arabia on Tuesday by revoking visas for agents implicated in the killing, a symbolic and ineffective move considering 18 of the 21 Saudi suspects were already under arrest.
He was pretty rough on Saudi Arabia, I would say.
Turkish President Tayyip Erdogan has said he would not let those responsible for Khashoggi's killing escape justice, and has urged Saudi Arabia to search from "top to bottom" to uncover those behind the killing.
Addressing a panel at the Future Investment Initiative conference in Riyadh, Prince Mohammed said that many parties were trying to exploit the incident to "drive a wedge between Saudi Arabia and Turkey".
But just hours before the face-to-face meeting, claims surfaced that he had ordered Mr Khashoggi's assassins to bring him his severed fingers as proof that the dissident was dead.
A State Department official told CNN that the suspects whose visas were being revoked would not be named due to "visa confidentiality".
CIA Director Gina Haspel has purportedly listened to an audio recording of the killing of Saudi writer Jamal Khashoggi at the hands of Saudi officials earlier this month in a consulate in Turkey, The Washington Post reported.
President Donald Trump on Tuesday also criticized the Saudi operation that killed Khashoggi, calling it one of the "worst cover-ups in the history of cover-ups".
The case has triggered an worldwide outcry against Saudi Arabia. "There obviously was a tremendous mistake made, and what compounded the mistake was the attempt to try to cover up".