At a conference in Bahrain, Adel al-Jubeir accused the western media of "hysteria" in its coverage of the case.
Saudi officials have also said he was accidentally killed in a botched security operation to return him to the kingdom.
The stance led to a clash with France's Macron who told reporters in the Slovak capital Bratislava on Friday that stopping arms sales to Saudi Arabia would be "pure demagoguery".
Kremlin said on Friday that Russian Federation has no reason to doubt the statements of the Saudi King and crown prince that the royal family was not involved in the killing of Khashoggi.
"The individuals are Saudi nationals, they're detained in Saudi Arabia, the investigation is in Saudi Arabia and they will be prosecuted in Saudi Arabia", he said at the Bahrain summit.
"First, we are gathered here to commiserate with the family and friends of journalist, Jamal Ahmad Khashoggi, and the good people of Saudi Arabia".
According to him, Saudi Arabia remained one of the most perilous places in the world for journalists, human rights advocates, and citizens critical of the monarchy government.
US Defense Secretary Jim Mattis said on Saturday that incidents like the killing of a Saudi journalist undermined Middle Eastern stability and that the United States would take additional measures against those responsible.
"We are making very clear that the United States does not tolerate this kind of action to silence Mr. Khashoggi, a journalist, through violence", he said.
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"Failure of any nation to adhere to worldwide norms and the rule of law undermines regional stability at a time when it is needed most", Mattis said.
"Just as we call on the Saudi government, so also we call on the Nigerian government to put an end to impunity for crimes against journalists", he said.
President Trump panned the shifting Saudi explanation. However, while he has floated the possibility of imposing sanctions. he has also stressed the importance of the two countries' ties.
At a conference in Riyadh on October 24, the crown prince said the killing was a "heinous crime that can not be justified" and warned against any efforts to "manipulate" the crisis and drive a wedge between Saudi Arabia and Turkey, which are regional rivals but also diplomatic and business partners.
Hatice Cengiz, in an interview with Turkish broadcaster Haberturk, said Khashoggi had not wanted to go to the Saudi consulate, where he was killed shortly after entering it on October 2.
The announcement contradicted an earlier Saudi assertion that rogue officials from the kingdom had killed Khashoggi by mistake in a brawl inside their Istanbul consulate.
How other key powers see the situation?
But there is disagreement over how to respond. "Without it, we weaken our security", he said, referring to the Gulf Co-operation Council nations.
On Friday, in Abuja, activists under the platform of the Coalition of Nigerian Media and Civil Society Groups demanded justice for Mr Khashoggi. "One shouldn't mix everything up", he said. "What we say to people is wait until everything is done" then decide if the investigation was serious or not.