EU foreign policy chief Federica Mogherini says the attacks in Paris give urgency to a meeting in Vienna of top officials from 20 countries and world bodies seeking solutions to the war in Syria.
In comments to the media just before the meeting began November 14, she called terrorism a global problem.
"The countries sitting around the table [in Vienna] have almost all experienced the same pain, the same terror, the same shock over the last weeks," she said.
Coordinated attacks in Paris on November 13 left 127 dead, a day after twin bombings in Beirut left 44 dead, and nearly two weeks after the downing of a Russian jet in Egypt killed all 224 on board.
French Foreign Minister Laurent Fabius said ahead of the Vienna meeting that the Paris attacks showed the need to strengthen the fight against Islamic State (IS) terrorists.
He said it is "more necessary than ever" to coordinate the antiterror fight and vowed no stop to French "international action."
U.S. Secretary of State John Kerry said that the attacks will "stiffen our resolve, all of us, to fight back."
"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," he said.
Russian Foreign Minister Sergei Lavrov said in Vienna that the Paris attacks "justify" the need to combat the Islamic State and Al-Nusra extremist groups.
Diplomats had modest expectations for the latest round of the Syrian peace talks in Vienna, which group top negotiators from Russia, the United States, Europe, and the Middle East.
"There are a number of difficult issues, of which the future of [Syrian President] Bashar al-Assad is probably the most difficult, and that will certainly be an important subject tomorrow," British Foreign Secretary Philip Hammond said after meeting his Egyptian counterpart Sameh Shukri on November 13.
Hammond echoed the assessment by Kerry, who said earlier that Assad's fate remains a major sticking point between the West and Gulf Arab states -- which want to see Assad step down -- and Assad allies Russia and Iran.
Kerry warned that a quick breakthrough was unlikely in the talks.
"I cannot say...that we are on the threshold of a comprehensive agreement," said Kerry, who arrived in the Austrian capital on November 13 for talks with his Saudi, Turkish, and UN counterparts.
"The walls of mistrust within Syria, within the region, within the international community are thick and they are high," he said.