Russian President Vladimir Putin on Sunday criticized the USA withdrawal from the Iranian nuclear deal in a speech at a regional summit in China.
"The very fact that we confirm the high level of our interaction and talk about the need for its development, in my opinion, is of great importance, for contemporary worldwide relations, for Russian-Chinese relations", he said.
He said: "Naturally we cannot force the United States to change their minds".
Trump has said he was open to having a summit with Putin, who USA intelligence officials have said directed Russian meddling in the 2016 election to help Trump win.
Russian Federation was expelled from the grouping in 2014 after it invaded and annexed Crimea and for its support for pro-Russia separatists in Ukraine.
"We did not (choose to) leave it, our colleagues refused to come to Russian Federation due to known reasons at some point".
Other leaders attending this weekend's G7 summit rejected Trump's idea.
"I think Putin's probably going, 'Man, I wish Hillary won, '" Trump said.
Britain blamed Russian Federation for the poisoning of the Skripals with a nerve agent in March in the British city of Salisbury, the accusations Moscow has vehemently denied.
The English-language Twitter of account of the Communist Party's People's Daily newspaper posted photos of a tense scene in La Malbaie, Quebec, and another of Xi and Putin smiling, with the caption, "G7 vs SCO: two meetings on the same day".
The China-Russia relations, standing at a high level, have benefited the two peoples and served as a model of harmonious coexistence of major countries and neighboring countries.
Now in the wake of the US withdrawal from the pact, "SCO members may use granting full membership to Iran as a way to demonstrate support for [Tehran] and the nuclear agreement", said Dawn Murphy, professor of worldwide security studies at the US Air War College.
While he's taken a tougher stance on traditional USA allies, Trump - who remains under investigation as part of an inquiry into potential collusion between his presidential campaign and the Kremlin - has charted a warmer course with Russian President Vladimir Putin.
He added that Russian Federation was ready to "develop, deepen and normalize ties with the United States", noting that the next move was for Washington to make.
Xi, whose government is locked in tough negotiations with the United States to avoid a trade war, said World Trade Organisation rules and the multilateral trading system should be upheld to build an open world economy.
Commentators questioned why the Trump administration would move to protect Russian interests at the expense of punishing them for alleged election interference.
He said that the U.S. exit from the nuclear deal warrants an "important and serious discussion between our two countries".