"At this point, we can't say when he will return to Syria," Toner said in a statement.
Meanwhile, Imad Moustapha, the Syrian ambassador to the United States, was recalled to Damascus "for consultations," embassy spokeswoman Roua Shurbaji said Monday.
Shurbaji had no information about why Moustapha was recalled or how long he will be gone. The deputy chief of mission in Washington will be filling Moustapha's role while he is gone, she said.
Ford was attacked by a pro-government "armed mob" last month, a United States official told CNN at the time. The official is not authorized to speak to the media and asked not to be named.
While there have been long-standing concerns about Ford's safety and threats against him, the decision was made to pull him temporarily after government-sponsored Syrian media began running false reports blaming Ford for death squads in Syria similar to the ones in Iraq, senior State Department officials told CNN.
The department was afraid the reports would inflame sentiment against Ford and would prompt pro-regime hardliners to harm and perhaps kill him, the officials said.
"We are concerned about a campaign of regime-led incitement targeted personally at Ambassador Ford by the state-run media of the government of Syria and we are concerned about the security situation that that has created," said State Department spokeswoman Victoria Nuland on Monday. "... I want to take this opportunity to call on the government of Syria to immediately end its smear campaign of malicious and deceitful propaganda against Ambassador Ford."
Ford, who has been outspoken against the Syrian government's use of violence against protesters, is seen by Syrian government supporters as an activist more than a diplomat.
He sparked a diplomatic firestorm in July when he traveled to the restive city of Hama to express support for demonstrators. He was welcomed with flowers by local residents who had suffered a brutal crackdown by government forces. President Bashar al-Assad's government called the trip an attempt to foment dissent.
A crowd tried to assault Ford and embassy colleagues September 29 "as they went about doing the normal work of any embassy," Toner said at the time.
"The mob was violent; it tried, unsuccessfully, to attack embassy personnel while they were inside several embassy vehicles, seriously damaging the vehicles in the process," Toner said.
Syrian security officers helped secure a path back to the U.S. Embassy for the ambassador and his staff.
U.S. Secretary of State Hillary Clinton condemned what she described as "an unwarranted attack" when Ford and his aides were conducting "normal embassy business."
The department does plan on sending Ford back, the officials said. It is hoped that his stay in the United States will be a brief cooling-off period and that the United States can persuade the Syrian government to abide by its obligations under the Vienna Convention to protect foreign diplomats in their country, they said.
"We do expect that Ambassador Ford will be returning to Damascus after his consultations are completed," Nuland said.
The department feels Ford serves a useful function as the United States' eyes and ears in the country, the officials said. In addition to serving as a witness to the regime's violence against protesters, he is seen as a key link to the opposition.
Ford was confirmed as ambassador to Syria in April after five years during which Washington did not have an envoy in Damascus.
Relations between Syria and the United States have been tense in recent months as Syria clamped down on demonstrations against Assad. At least 3,000 people have died, the United Nations and other international observers estimate.
Earlier this month, a Syrian man was arrested in the United States, accused of spying on Syrians demonstrating in the United States. Syria rejected the indictment's claim that Mohamad Anas Heitham Soueid worked for Syria's intelligence agency, the Mukhabarat.
And it described as "ludicrous" the indictment's assertion that Soueid, a Syrian-born American citizen, had met privately with Assad.
