"Iran and Syria have been strategic partners for more than four decades and this alliance has been the main obstacle to foreign aggression in the region," Miryousefi told Newsweek on Saturday.
"Iran proudly continues its help for the Syrian government in order to maintain its territorial integrity and protect its people from terrorist groups," he added.
Miryousefi said the only effective mechanism for Syria in the past nine years has been the Astana process, which includes the cooperation between Iran, Syria, Russia and Turkey.
His comments came after the US in a statement defended Washington’s policy in Syria amid heated criticisms, with the State Department calling for the withdrawal of Iran from the Arab country.
A spokesman for the US State Department told the Newsweek that US policy objectives for Syria are "the enduring defeat of ISIS [Daesh] and Al-Qaeda, an irreversible political solution to the Syrian conflict in line with UNSCR 2254, and the removal of all Iranian-supported forces."
Iran has been providing Syria with advisory military assistance after numerous countries, at the head of them the US and its Western and regional allies, started funding and arming militants and terrorists with the aim of deposing the Syrian government.
Miryousefi called the US an "uninvited intruder in the region and in Syria," accusing it of having "done nothing but increase insecurity and impose more suffering on the Syrian people" by supporting terrorist groups attempting to topple Syrian President Bashar al-Assad and imposing sanctions.
"The US and its allies have openly supported extremist groups in Syria, from Al-Nusra to Ahrar al-Sham and other terrorist groups for years, and most recently, imposed new sanctions, called 'Caesar', on the war-weary Syrian people," Miryousefi said.
"These acts undermine the US' crocodile tears for the Syrian people," he added.
The US State Department’s statement was also rejected by Moscow and Damascus. In a joint statement Thursday, they condemned the "illegal presence of the United States of America and its allies on the territories of the sovereign Syrian state."
The statement pointed to the US Office of Foreign Asset Control's recent licensing of a US oil company to operate in northeastern Syria. The two governments said such agreements "violate the rules of international law and violate Syria's sovereignty and territorial integrity."
"Besides the clear violation of international law, American presence in Syria has an undeniable negative impact on the lives of Syrians," Nikolay Lakhonin, a spokesperson for the Russian Embassy in Washington, recently told Newsweek. "By occupying major oil and gas reserves in the northeast, the US deprives the people of Syria from its own vital resources."
In remarks earlier sent to Newsweek by Syria's mission to the United Nations, Damascus' permanent representative to the UN Bashar al-Ja’afari said the US and the Syrian Democratic Forces were "stealing Syrian oil and depriving the Syrian state and Syrian people of the basic revenues necessary to improve the humanitarian situation, provide for livelihood needs and reconstruction."