Residents of the Syrian capital expressed skepticism on Monday about reports that a "provisional agreement" has been reached for a truce, a day after a wave of Islamic State bombings killed about 130 people in government-held areas near Damascus and beyond.

Details of the tentative cease-fire, announced in Jordan on Sunday by U.S. Secretary of State John Kerry, have not been made public. Even if a truce were to take hold, the Islamic State is not party to any such cease-fires or negotiations for a truce.

In a possible sign of some breakthrough, the Russian Foreign Ministry put out a statement Monday saying that Russian Foreign Minister Sergey Lavrov and Kerry spoke two more times by telephone on Sunday evening and during the course of their conversations agreed on the parameters for the cease-fire in Syria.

The statement said these parameters were then reported to Russian President Vladimir Putin and President Barack Obama. No further details were immediately available.

Sunday's blasts that ripped through the Sayyida Zeinab suburb of Damascus and the central city of Homs were among the deadliest bombings in government-held areas in Syria's devastating five-year civil war.

The Islamic State group claimed both attacks. The extremists are dug in on the outskirts of the two cities and have repeatedly targeted pro-government strongholds.

The mood in government-controlled Damascus was weary on Monday. Inside the Hamidiyeh Souk, a popular bazaar which is typically crowded with shoppers, people said they were worried that a ceasefire would not be evenly observed and could leave the Syrian authorities vulnerable.

"I hope there will be no ceasefire. Because if there is a ceasefire, Turks will increase their support for criminals and traitors," said Ahmad Al-Omar from the northern Aleppo province, adding that Turkey may seek to let opposition fighters in via its border with Syria.

Others at the bazaar echoed President Bashar Assad's statements that a ceasefire could give an advantage to rebel forces and also the Islamic State group.

"I believe that those proposals now are ... a pretext to stop the advance of the Syrian army which is trying to liberate the homeland," said Ahmad Al-Issa.

Sunday's blasts came as Kerry announced that a "provisional agreement" has been reached on a cessation of hostilities that could begin in the next few days. But he acknowledged that it's not finalized and all parties might not automatically comply.

Kerry declined to go into the details of the agreement, saying it "is not yet done."

"The modalities for a cessation of hostilities are now being completed," Kerry said, adding that it was "possible over the course of these next hours."

The Damascus authorities said the government was ready to take part in a truce as long as it is not used by militants to reinforce their positions. Syrian troops, backed by Russian warplanes are on a major offensive in the northern Aleppo province, trying to seal the border with Turkey, a key supporter of the rebels, before any truce is reached.

Meanwhile, the Syrian government's supply route by land to the city of Aleppo was cut by heavy fighting Monday as the army, supported by allied militias and the Russian air force, fought to consolidate its recent gains in the northern province.

The Britain-based Syrian Observatory for Human Rights, which relies on a network of contacts to monitor the war, said Islamic militias assaulted government-held positions around Khanaser, a town southeast of Aleppo, setting off intense clashes that have lasted through the day. Khanaser lies along the government's only access route to Aleppo.

Aleppo, Syria's largest city and one-time commercial center, is divided between the government and its opponents, while ISIS holds a wide front to the east of the city.

Fighting has been fierce in Aleppo province in recent weeks amid a government offensive to cut off the rebel stronghold.

The Russian Foreign Ministry put out a statement on Monday condemning Sunday's bomb blasts in Damascus and Homs and calling for a "proper, principled response" from the international community to prevent terrorist groups from further aggravating the situation in Syria and inciting sectarian strife.

"The brutal crimes by extremists are aimed at intimidating the civilian population and undermining attempts to achieve a lasting political settlement of the Syrian crisis in the interests of all Syrians and efforts to end the violence and bloodshed," the Russian statement said.