Officials from the United Nations, the United States and Arab countries have been meeting in the Swiss city of Geneva to discuss the Syrian crisis.
The February ceasefire stopped much of the fighting in Syria for the first time in five years.
But it has broken down as government forces and the opposition battle for Aleppo, where hundreds of people have been killed in the past week.
Saudi Foreign Minister Adel al-Jubeir has described the escalation of violence as a tragic violation of humanitarian law.
"The indiscriminate bombings of civilians is unacceptable. The bombings of hospitals and killing of patients and doctors and women and children is a criminal act for which we uphold the Bashar Al-Assad regime responsible, along with their allies."
Mr Jubeir says the international community must not allow President Assad to remain in power.
"The world is not going to allow them to get away with this and Bashar Al-Assad's days are numbered. He will leave, he can leave through the political process which we hope he will do, or he can be removed by force. The man who murdered 400,000 people, displaced 12 million people in the country has no future in that country."
Speaking after talks in Geneva, the U-S Secretary of State John Kerry was more restrained.
John Kerry says both sides are to blame for the escalation in fighting.
In an attempt to salvage the fragile ceasefire, Mr Kerry has announced a deal with Russia to improve its monitoring.
"Russia and the United States have agreed that there will be additional personnel who will work from here in Geneva on a daily basis, 24/7, in order to, 24 hours a day, seven days a week, in order to try to make sure that there is a better job and better ability to be able to enforce the cessation of hostilities day to day."
The United Nations Special Envoy for Syria, Staffan De Mistura, has stressed that peace talks can only proceed smoothly once all sides stopped the fighting.
"We are preparing the mechanism but a mechanism needs a political will otherwise we will have only a mechanism but that is actually being started; preparing for a much better mechanism for monitoring and controlling a new ceasefire, reinvigorated, but we need political will for that."
Meanwhile, Syrian state media is reporting that the Syrian military has extended the temporary ceasefire around the capital Damascus and the coastal Latakia region.
"The general command of the army and the armed forces announced the extension of the deescalation system in Damascus and the eastern Ghouta for an additional 48 hours."
The United States wants that truce extended to Aleppo, where hundreds of civilians have been killed in government air strikes and rebel shelling in the past week alone.
But White House spokesman, Josh Earnest, has rejected calls for the U-S to enforce so-called "safe zones" in the country.
Mr Earnest says the priority for the U-S and coalition forces is to defeat the so-called Islamic State, also known as ISIL.
"The focus of our military should be on degrading and destroying ISIL. The Assad regime needs to live up to the commitments that they have made and we would like to see the Russians use the influence that they have, with the Assad regime, to get them to do it."
Director of the C-I-A, John Brennan, has revealed the fight against I-S has been harder than anticipated.
"It gained strength very quickly, quicker than we thought. It has set up a so-called caliphate. It has put its roots down in territory. It has been able to attract a number of individuals from outside of that Syrian-Iraq area, over tens of thousands of individuals who have traveled to join this so-called caliphate. So I think it has had a resonance, unfortunately, that has appealed to the hearts and souls and minds of individuals who have been mislead by their narrative of it being a religious banner."
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