US Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov both condemned the attacks as they began meetings with senior representatives from Iran, Saudi Arabia and other countries with strongly conflicting views on how to end the more than four-year war.
Key differences include what, if any role Syrian President Bashar Assad should play in any transition government and which groups fighting him should be grouped as terrorists.
"These kinds of attacks are the most vile, horrendous, outrageous, unacceptable acts on the planet," said Kerry, sitting with other somber-looking ministers and their deputies at the negotiating table in a luxurious Vienna hotel.
"And the one thing we could say to those people is that what they do in this is stiffen our resolve, all of us, to fight back, to hold people accountable, and to stand up for rule of law, which is exactly what we are here to do.
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"And if they've done anything, they've encouraged us today to do even harder work to make progress and to help resolve the crises that we face," Kerry said.
Ahead of the meeting, French Foreign Minister Laurent Fabius said the attacks in Paris made it all the more necessary for the international community to find a common approach in Syria and terrorism.
The foreign ministers of Germany, Jordan and Saudi Arabia echoed Fabius' sentiments. Jordan's foreign minister, Nasser Judeh, said the Paris attack "reaffirms our collective commitment" to fight terror and extremism wherever it may occur.