For the prince, it's about the killing of a dissident Saudi journalist in the country's Istanbul consulate.
In contrast, Mr Putin and the crown prince shared a smiley, enthusiastic greeting at the gathering.
The Argentine judiciary has initiated steps toward a formal investigation of Saudi Crown Prince Mohammed bin Salman's possible responsibility for war crimes in Yemen and alleged torture of Saudi citizens.
Less than two months after Saudi Arabia outraged allies when a hit team murdered Jamal Khashoggi in the kingdom's Istanbul consulate, Prince Mohammed flew into Buenos Aires to take his place among leaders of the top 20 global economies, a sign that he intends to remain firmly in charge.
Theresa May used a meeting with the Saudi Crown Prince at the G20 summit to "encourage" him to make sure Saudi Arabia co-operates in the investigation into murdered journalist Jamal Khashoggi.
Macri has said accusations that Prince Mohammed was involved in Khashoggi's death could be discussed by world leaders during the two-day summit.
However, French President Emmanuel Macron took a cooler, more confrontational stance when he came face-to-face with the Saudi crown prince.
Apple Stock Drops as Trump Discusses Potential iPhone Tariff
The U.S.is due to raise import duties on about $200 billion worth of goods from China to 25 percent from 10 percent on January 1. China has retaliated but has less room to manoeuvre as the United States buys much more from China than it exports there.
Jahana Hayes says she supports Pelosi for house speaker
Jeffries said the caucus will be "member-driven" and focus "like a laser beam" on making sure they have a successful two years. Ms Pelosi was the first woman to be speaker when Democrats had the House majority from 2007 to 2011.
North London derby is bigger for Arsenal than Totenham, says Paul Merson
Tottenham must still beat Barcelona on December 11 at the Camp Nou to make sure of advancing to the knockout phase. Both men are back in training, but neither have been given the all-clear to get involved in this game.
Saudi-owned broadcaster Al Arabiya posted video on Twitter showing a cordial handshake between bin Salman and Chinese President Xi Jinping as the two held a bilateral meeting.
Macron told Prince Mohammed that Europeans wanted worldwide investigators to take part in the probe on Khashoggi's death and stressed "the necessity of a political solution in Yemen", the Elysee Palace said.
At the end Mr Macron can be heard saying: "I am a man of my word". Saudi authorities eventually admitted Khashoggi had been murdered.
There has been widespread condemnation and public outrage over attacks on sites such as school bus and hospitals, where Yemeni civilians, including children, have died.
G20 powers opened two days of summit talks, after a stormy buildup dominated by tensions with Russian Federation and US President Donald Trump's combative stance on trade and climate fears.
White House spokesperson Sarah Sanders insists the reason for the cancellation was the situation with Ukraine, but said the probe into possible collusion between the Trump presidential campaign and Russian Federation was damaging ties between the two countries.
The two leaders also explored investing in solar energy through Softbank's Saudi-backed Vision Fund and opportunities to export Saudi non-oil products to India.