"We have got to end this war; we will carry on going until we do end this war," Matthew Rycroft told CNN's Christiane Amanpour
"At its core, Daesh is taking advantage of chaos in Syria," he said, referring to the terror group ISIS.
"Every single attack, whether it is in Paris
, in Istanbul
, or anywhere else, redoubles the resolve of the international community."
An ISIS-claimed attack Thursday
killed at least two and wounded 19 in Jakarta, Indonesia. Turkish officials also blame the terror group for Tuesday's suicide bombing in Istanbul's Sultanahmet Square
that left 10 German tourists dead. Both of this week's attacks followed the November massacre in Paris
in which terrorists linked to ISIS killed 130 people.
ISIS' power stems from the Syrian conflict, which has grown more complex in recent months, with Russia's military intervention and a fallout in diplomatic relations between the region's two most powerful players -- Iran and Saudi Arabia.
World powers still push for a diplomatic solution, but such talks in the nearly 5-year-old civil war have ended in complete failure.
The British government soon will jointly host a donors' conference to raise humanitarian funds, and Rycroft said he hoped that peace talks in Vienna, Austria, would resume at the end of the month.
Those talks, crucially and for the first time when they began last year, have included both Saudi Arabia and Iran.
"Look, we've known all along that Saudi Arabia and Iran have very different and opposite views on the future of Syria and on so many other issues.
"But the Vienna process has as one of its strengths the fact that those two countries are both inside that single tent."
Meanwhile, Russia has used its intervention in Syria not to go after ISIS, as it said it would, Rycroft said.
"Instead they have gone and the majority of their airstrikes have been against the opposition -- some of whom have been named as participants in these future peace talks."
But his optimism for the year ahead, he said, dictates that the United Kingdom and its allies continue to "reach out and include" Russia.
"They have a very important role to play, and we've seen in these Vienna talks co-chaired by (U.S. Secretary of State John) Kerry and (Russian Foreign Minister Sergey) Lavrov that they have an important role to play. And I urge them to play it."