US President Barack Obama led international praise for the demonstrators who have taken to the streets calling for Ben Ali to hand over the reins of power in the tightly controlled north African country.
"I applaud the courage and dignity of the Tunisian people," Obama said in a statement, as he appealed for calm after weeks of violent protests in which dozens of people have been reported killed.
"The United States stands with the entire international community in bearing witness to this brave and determined struggle for the universal rights that we must all uphold, and we will long remember the images of the Tunisian people seeking to make their voices heard," he added.
Like other leaders, he urged Tunisian authorities to uphold promises that free and fair elections will now be held.
Ben Ali, who was once seen as an ally of the US, fled Tunisia for Saudi Arabia in a dramatic end to his 23 years in power following a wave of social protests.
Tunisian Prime Minister Mohammed Ghannouchi, who announced Friday that he had taken over as interim president, has vowed to enact social and political reforms, and said fresh elections would be held within six months.
Obama said such elections must "reflect the true will and aspirations of the Tunisian people," and he argued "that each nation gives life to the principle of democracy in its own way, grounded in the traditions of its own people."
UN Secretary General Ban Ki-moon called Friday for a "democratic outcome" to Tunisia's crisis.
"The secretary general calls for full respect for freedom of expression and association and urges all concerned parties to seek to resolve issues peacefully and lawfully with the goal of addressing grievances as well as to work towards a democratic outcome that responds to the aspirations of the Tunisian people," said a UN statement.
Ban "is closely monitoring events in Tunisia and will continue to do so," said the UN.
After much speculation, Ben Ali's plane landed early Saturday in Jeddah, Saudi Arabia, after former colonial power France said he was not welcome.
It was not clear however if the Red Sea city was to be his final destination.
"We don't want him to come, there's no chance he'll be allowed to land," a source close to French government thinking told AFP earlier.
French President Nicolas Sarkozy's office said only that it had taken note of the constitutional change in Tunisia and called for an end to violence.
The European Union also called for a lasting solution in Tunisia as EU chief diplomat Catherine Ashton voiced "support and recognition to the Tunisian people and their democratic aspirations, which should be achieved in a peaceful way."
"Dialogue is key. We reiterate our engagement with Tunisia and its people and our willingness to help find lasting democratic solutions to the ongoing crisis," said the EU statement also from enlargement commissioner Stefan Fuele.
The Tunisian authorities have declared a state of emergency and British Foreign Secretary William Hague on Friday also condemned the violence.
"I am calling for a rapid return to law and order, restraint from all sides, an orderly move towards free and fair elections and an immediate expansion of political freedoms in Tunisia," Hague said in a statement.
The Foreign Office and the United States have advised against all but essential travel to the favorite tourist destination and one of Europe's biggest tour operators, Britain's Thomas Cook, said Friday it was evacuating 1,800 British and Irish holidaymakers from the country.
Analysts said the abrupt change of power in Tunisia was likely to send shockwaves around a region dominated by veteran leaders like the 74-year-old Ben Ali.
In Cairo, demonstrators streamed towards the Tunisian embassy singing, chanting and urging Egyptians to follow the example of Tunisians.
"Listen to the Tunisians, it's your turn Egyptians!" chanted the demonstrators, surrounded by heavy security.
Egyptians have complained of similar economic hardships as Tunisians, and Cairo has regularly come under criticism for failing to lift an emergency law in place for three decades.
Ben Ali came to power in a bloodless coup in 1987 at a time of stagnation for Tunisia and he was initially hailed by many people for enacting liberal economic reforms as well as nipping in the bud the Islamist Ennahdha party.
In a bid to make concessions in recent days, Ben Ali had sacked some regime loyalists and promised to stand down at the end of his current mandate in 2014, as well as to lower the prices of basic foodstuffs.
But his promises ultimately failed to quell the anger in the streets.