The killing of journalist Jamal Khashoggi at the Saudi consulate in Istanbul was a "rogue operation", Saudi Arabia's foreign minister said.
Adel al-Jubeir said that those responsible will be held accountable for "this huge and grave mistake".
He extended his condolences to the family of the journalist.
"We can feel their pain and we wish this didn't happen and I wish that this could have been avoided," he said in an interview with Fox News.
Saudi Arabia finally admitted on Friday that its agents killed Mr Khashoggi after he entered the consulate on October 2, but denies that Crown Prince Mohammed bin Salman or King Salman were involved.
Mr Al-Jubeir echoed President Donald Trump's warnings against rushing to judgment against Saudi leaders, saying "there is the presumption of innocence until proven guilty," and that some have "turned that upside down".
He added that Saudi officials do not know the whereabouts of Mr Khashoggi's remains.
The kingdom has also said 18 suspects are in custody and that intelligence officials have been fired.
A bipartisan group of US lawmakers has accused the Crown Prince of directing the operation. South Carolina Senator Lindsey Graham said: "I find it impossible to believe that the Crown Prince was not involved."
Mr Trump said he would talk to the Crown Prince "very soon" before deciding what to do next.
He said he planned to consult with Congress to devise a response. "We'll have an answer by probably Tuesday or so," he said.
Mr Trump has repeatedly said over the last week that he opposes any effort to impede more than $100 billion in US arms sales to Saudi Arabia, but that he would consider sanctions on the kingdom.
On Friday, asked if he believed whether the Saudi explanation that Mr Khashoggi was killed during a "fistfight" with more than a dozen agents was credible, he said: "I do. I do."
But on Saturday, in an interview with The Washington Post, Mr Trump said, "Obviously there's been deception and there's been lies."
Mr Khashoggi, a prominent journalist and royal court insider for decades in Saudi Arabia, had written columns critical of Crown Prince Mohammed bin Salman and the kingdom's direction while living in self-imposed exile in the US. He went to the Saudi consulate to obtain paperwork for his forthcoming marriage.
"The Saudi 'explanation' for murdering journalist and Virginia resident Jamal Khashoggi in a consulate - a fistfight gone wrong - is insulting," tweeted Senator Tim Kaine, the 2016 Democratic vice presidential nominee. "Since the Trump Administration won't stand up against atrocity, Congress must."
Democratic Representative Adam Schiff of California said Saudi Arabia's claim that Mr Khashoggi died in a brawl was not credible.
"If Khashoggi was fighting inside the Saudi consulate in Istanbul, he was fighting for his life with people sent to capture or kill him," said Mr Schiff, a member of the House Intelligence Committee.
"The kingdom and all involved in this brutal murder must be held accountable, and if the Trump Administration will not take the lead, Congress must," he said.
Journalist Jamal Khashoggi was killed in a "fistfight" in the Saudi consulate in Istanbul, the kingdom has said as it admitted the writer had been slain at the diplomatic post for the first time.