Russia has decided not to attend the US-led international conference inaugurated yesterday in Polish capital Warsaw.
The Russian Foreign Ministry said on social media that the meeting "is a new US attempt to promote its unilateral geopolitical interests through initiatives that are presented as the opinion of the international community".
Russia also denounced the US attempts to affect decision making in Iran, Al-Sharq Al-Awsat reported, citing the Russian Interfax news agency.
Iranian President Hassan Rouhani was reported by Interfax as saying: "The conspiracy of big countries like America will not affect our policies."
The US, which believes that Iran is developing a nuclear bomb, claims it will push the Iranian army out of Syria.
Chief EU diplomat Federica Mogherini also said she would not attend the Warsaw conference, Al Jazeera said, adding that Lebanese Foreign Minister Gebran Bassil had also announced he would not attend the summit.
Meanwhile, Palestinian officials have dubbed the conference a US-Israeli "conspiracy aimed at eliminating the Palestinian cause".
Instead of attending the conference, Russian President Vladimir Putin plans to receive Turkish President Recep Tayyip Erdogan and Iran's Rouhani in Moscow today, to discuss plans related to Syria in response to the US withdrawal announcement late last year.