Trump breaks silence over Saudi journalist disappearance
"I am concerned. I don't like hearing about it. Hopefully that will sort itself out," Trump told reporters at the White House on Monday.
"Right now, nobody knows anything about it. There are some pretty bad stories going around. I do not like it."
Vice President Mike Pence has also spoken out over the saga, saying he was "deeply troubled" about reports of Khashoggi's fate.
"If true, this is a tragic day. Violence against journalists across the globe is a threat to freedom of the press & human rights. The free world deserves answers," Pence said on Twitter.
Jamal Khashoggi, who is an opinion page contributor at the Post, disappeared after visiting the kingdom's consulate. A Turkish government source said he was killed inside, but Saudi Arabia says that the journalist left the building.
Read more: Lies, murder and deceit: the daily reality of Mohammed Bin Salman's war on dissent
Turkish President Recep Tayyip Erdogan on Monday said that Saudi Arabia must "prove it with footage."
The US is a close ally of Saudi Arabia and rarely dares to criticise its appalling human rights records.
In March, the kingdom's de facto leader crown prince Mohammed bin Salman, who many accuse of being behind Khashoggi's disappearance, went on a high-profile tour of the US.
Bin Salman was warmly welcomed not only in the White House but also among influential American business and technology figures such as Bill Gates and Jeff Bezos, the owner of the Washington Post, and discussed investment opportunities for the kingdom's Vision 2030 programme.
During his visit, prominent US figures and media outlets praised the young leader for his reforms in the kingdom, turning a blind eye to the rampant human rights violations in the country.
Join the conversation by tweeting us @the_newarab