The Syrian government does not cooperate with the UN Human Rights Council (UNHRC) believing that the body is propagating the anti-Syrian policy of western countries, Syrian Deputy Foreign Minister Faisal Mekdad said.
Regime forces have advanced rapidly through farmland in the enclave since last week, according to the Observatory, taking control of more than half of the territory from the armed opposition.
The UN has called the bombardment "unacceptable", saying it amounts to "the collective punishment of civilians".
Within the last eight months, the regime has stepped up the siege, preventing food and medicine from entering the district, leaving thousands of residents in need of medical treatment.
The correspondent said the men were fighters who had come out of eastern Ghouta through the al-Wafideen crossing into government-held Syria.
The Syrian government denied the accusations, saying it is the rebels who mounted the attack to frame the government and draw in a military action from the United States.
Misraba is located along a major road that links Douma, in the north, with another big town, Harasta, in the west.
Syrian government forces have split the rebel-held enclave of Eastern Ghouta, cutting off the largest city Douma, media reports said on Saturday.
Mohammad Alloush, one of Jaish al-Islam's leaders, told pan-Arab television channel al-Arabiya al-Hadath on Friday that there are no more than "a few hundred" Nusra fighters in Eastern Ghouta, Reuters reported. President Bashar al-Assad vowed last week that Syrian forces would continue the campaign until the whole area is retaken.
During rebel infighting in the enclave, analysts and some residents say, the Army of Islam's main rival, Faylaq Al Rahman, has sometimes formed opportunistic alliances with H.T.S. They encompass multiple factions, including jihadists, and in-fighting between them has led to past losses of ground to the Syrian government.
"It has been agreed that the first group of HTS members be released from the prisons of Jaish al-Islam".
The Syrian government is desperate to regain the territory, and has said its attempts to recapture it can be attributed directly due to the HTS presence there.