Standing outside the presidential residence flanked by supporters, Rousseff insisted on her innocence and said her removal was a "parliamentary coup" backed by the economic elite that would roll back social programmes that lifted millions of Brazilians out of poverty over the last decade.
"They think they have beaten us but they are mistaken," Rousseff said, adding that she would appeal the decision using every legal means.
"At this time, I will not say goodbye to you. I am certain I can say 'See you soon'."
In an unexpected move, Brazil's Senate voted 42-36 to allow Rousseff to retain the right to hold public office - in a break with Brazil law that specifies a dismissed president should be barred from holding any government job for eight years.
The move appeared to demonstrate unease among some senators, notably within Temer's own fractious Brazilian Democratic Movement Party (PMDB), over whether a budgetary sleight of hand that is common in Brazil was truly an impeachable offence.
Meanwhile, leftist leaders in Caracas, Quito, La Paz and San Salvador have been consistent allies of Rousseff and her predecessor, Luiz Inacio Lula da Silva, including Venezuelan President Nicolas Maduro, who said the US was behind the impeachment push.
"This coup d'etat isn't just against Dilma. It is against Latin America and the Caribbean. It is against us," Maduro said in a televised speech.
"This is an attack against the popular, progressive, leftist movement."
Brazilian Foreign Minister Jose Serra defended the constitutionality of Rousseff's impeachment and questioned the legitimacy of Maduro's Government.
"The Venezuelan Government has no moral standing to talk about democracy, since they don't have a democratic regime," he said.
A political crisis in Venezuela has already heightened tensions with the Temer Government, which took over on an interim basis when Rousseff was suspended in May to face trial.
Last month, diplomats from Brazil and Uruguay traded barbs over the latter's accusation that Brasilia was trying to "buy" its vote to block Venezuela from taking the rotating presidency of the region's Mercosur trade bloc.
Brazil, Argentina and Paraguay have refused to allow Venezuela to take the Mercosur presidency, arguing that it has not complied with the minimum requirements to belong to the common market.
Adding its voice to the criticisms, the leftist Government of El Salvador said in a statement that Rousseff's removal "represented a serious threat for Latin America's democracy, peace, justice, development and integration."
The US State Department voiced confidence that strong bilateral relations with Brazil would continue, adding the country's democratic institutions had acted within the constitutional framework.
- Reuters, AP
