Wen's remarks were the highest-level response to last week's rampage in Lhasa, which the government said killed 16 people and injured dozens and which focused world attention on China's human rights record ahead of this summer's Beijing Olympics.
The hardline stance taken by the normally mild-mannered premier underscored the communist leadership's determination to regain control over the region and ensure a smooth run-up to the games.
"There is ample fact - and we also have plenty of evidence - proving that this incident was organized, premeditated, masterminded and incited by the Dalai clique," Wen told reporters at a news conference held at the end of China's national legislative meeting. He gave no details.
"This has all the more revealed that the consistent claims made by the Dalai clique that they pursue not independence but peaceful dialogue are nothing but lies," he said.
Wen underscored that China will only consider dialogue with the Dalai Lama if the exiled spiritual leader was "willing to give up his proposition for so-called Tibetan independence."
"This is the position we have made for dealing with this issue," Wen said, "and this position remains unchanged."
Hours after Monday's midnight deadline for protesters to turn themselves in or face severe punishment, the U.S. government-funded Radio Free Asia on Tuesday quoted an unnamed witness as saying that authorities in Lhasa had began arresting hundreds of people.
No details were given and the report could not be independently confirmed because of China's tight control over information and ban on trips by foreign reporters.
Police in Lhasa refused to answer any questions.
The Lhasa protests, led by monks, began peacefully March 10 on the anniversary of a failed uprising in 1959 against Chinese rule. Tibet had been effectively independent for decades before Chinese communist troops entered in 1950.
They grew increasingly violent, culminating Friday with widespread street violence in Lhasa. Champa Phuntsok, Tibet's China-appointed governor, said Monday that the death toll from the unrest had risen to 16 and that dozens were injured. He denied a claim by the Dalai Lama's government-in-exile in India that 80 Tibetans died.
Wen said the protesters killed bystanders and smashed public utilities and cars. They also set fire to stores, he said.
"They used extremely cruel means," Wen said. "This incident has seriously disrupted public order and life in Lhasa. This incident has inflicted heavy losses of lives and property of the people in Lhasa."
However, Wen said, Lhasa was returning to normal.
"The situation is quiet and calm, and Lhasa will be reopened to the rest of the world," he said.
An official at the Administrative Department of the city's Communist Party office said Tuesday the city's markets, work places, schools were all back in operation.
"There are no police or troops around our area. But as to whether there are still police sealing off the downtown streets, I am not clear yet," he said. He refused to give his name.
A receptionist at the Tibet International Grand Hotel said there were less police on patrol. "So far there has been no police raid or visit to our hotel," she said.
On Monday, Chinese Foreign Ministry spokesman Liu Jianchao insisted that Beijing would "unwaveringly protect its national sovereignty and territorial integrity" and accused the Dalai Lama's supporters of being behind sometimes violent demonstrations at Chinese embassies and consulates in the U.S., Europe and Asia since Friday.
On Tuesday in Sydney, Australia's largest city, protesters burned Chinese flags and scuffled with police outside the Chinese consulate.
Protests inside China have spilled from Tibet into neighboring provinces and even the capital, Beijing, where students staged a vigil Monday.
The communist government in Beijing wants to ensure that the Aug. 8-24 Summer Olympics boosts its international image, rather than draw unwelcome attention on its rights record.
"This is a China engaged with the world which is using the Olympics to demonstrate a new openness, and it risks all of that collapsing in on it if it is seen as being the enforcer of a crackdown on Tibetans," said Mark Malloch-Brown, the British Cabinet minister in charge of Asia relations.
But Wen insisted that the Games would be "a grand gathering for people from around the world" and that they should not be politicized - a position often reiterated by China.
Wen also dismissed claims by the exiled Dalai Lama that there was "cultural genocide" taking place in the revered spiritual leader's homeland.