Iran and China have warned against any foreign intervention in Syria, stressing that the future of the war-hit country must be decided only by its people.

The warning on Tuesday came after President Barack Obama said the US was sending 250 additional special forces Syria.

"No foreign power must interfere in issues related to Syria's future. We must allow the Syrian people to decide for themselves about writing a new constitution and choosing a president," China’s envoy for Syria Xie Xiaoyan said.

He made the remarks during a meeting in Tehran with Iran’s Deputy Foreign Minister Hossein Amir-Abdollahian who stressed the importance of a sustainable campaign against terrorists in Syria.

"The agreement reached at the International Syria Support Group (ISSG) meeting (in February) was that the fight against terrorism seriously be put on the agenda in parallel with political talks," he said.

"However, we unfortunately see that no serious global measure is being taken in the battle against terrorism,” Amir-Abdollahian added.

The two officials also voiced support for the efforts made by the UN Special Envoy for Syria Staffan de Mistura to find a political solution to the crisis.

Referring to the close ties between the armed opposition groups and the terrorist groups in Syria, Amir-Abdollahian said, “The Americans have also admitted that it is hard to tell terrorist groups from other gunmen.”

Syrian army soldiers patrol in the town of Deir Hafer, a former bastion of the Daesh terrorist group, near the city of Aleppo, December 2, 2015. (Photo by AFP)

The Chinese official, for his part, underlined his country's call for a political solution to the Syrian conflict.

Describing the situation in Syria as “complicated,” Xie said the Syria peace talks should be given time to produce results.

Syria has been gripped by foreign-backed militancy since March 2011. According to de Mistura, at least 400,000 people have been killed in the conflict. Some reports, however, put the death toll at as high as 470,000.