The US and France have condemned a speech by Syrian leader Bashar al-Assad which blamed an "external conspiracy" for the mass uprising against his rule.
The US state department said President Assad had thrown "responsibility on everybody but back on himself".
France's foreign minister said the speech amounted to "denial of reality".
In a rare public address, Mr Assad said international powers were trying to destabilise Syria, and vowed to crush "terrorists" with an "iron fist".
In Washington, state department spokeswoman Victoria Nuland said: "Assad manages to blame a foreign conspiracy that is so vast with regard to the situation in Syria that it now includes the Arab League, most of the Syrian opposition, the entire international community.
"He throws responsibility on everybody but back on himself and with regard to his own responsibility for the violence in Syria."
She added that the address confirmed "our view that it is time for him to step aside".
Speaking in Paris, French Foreign Minister Alain Juppe said: "It incites violence and confrontation between the parties. It's a sort of denial of reality."
Attack on monitors
Tuesday's speech was President Assad's third televised address since protests against his rule began in March, and lasted nearly two hours.
"Regional and international sides have tried to destabilise the country," he said.
"Our priority now is to regain the security in which we basked in for decades, and this can only be achieved by hitting the terrorists with an iron fist.
"We will not be lenient with those who work with outsiders against the country."
The Syrian authorities say they are fighting armed groups, and that about 2,000 members of the security forces have been killed so far.
In recent months, army deserters have joined the opposition and targeted government forces.
A team of 165 monitors from the Arab League has been in Syria since December to monitor implementation of a peace plan that calls for an end to violence, the removal of heavy weapons from cities and the release of political prisoners.
Opposition groups have accused the mission of serving to cover up the crackdown on the protests, which has continued despite the presence of the observers.
Reacting to the speech, the head of the opposition Syrian National Council, Burhan Ghalioun, said Mr Assad's emphasis on restoring order "means he is backing away from his own pledge to the Arab League plan".
Meanwhile, the Arab League has condemned a recent incident in which two members of its observer mission were injured in an attack.
The Kuwaiti monitors were set upon by unidentified assailants as they drove to the port city of Latakia, a stronghold of President Assad.
"Failing to provide adequate protection in Latakia and other areas where the mission is deployed is considered a serious violation by the government of its commitments," the league said in a statement.
Syrian Foreign Minister Walid Muallem denounced the attack, saying his government "would continue to bear its responsibility to secure and protect those monitors".
In his speech, Mr Assad also said Syria would not "close its doors" to an Arab solution as long as "it respects Syria's sovereignty".
There were no obstacles to a multi-party system, he said, adding that it was a question of time.
Mr Assad said he welcomed the idea of expanding the government to include "all political forces".
A referendum on a new constitution could be held in March, he said, paving the way for elections in May or June.
In the latest fighting, the Local Co-ordination Committees, a network of anti-government activists, said 35 protesters had been killed on Tuesday, including 17 in the eastern city of Deir al-Zour.
The UN on Tuesday said 400 people have been killed by security forces since the start of the observer mission.
Last month the UN put the death toll since March at 5,000.