Syrian opposition forces would welcome "any kind of help" from allies such as the UK, the leader of the moderate coalition said after talks with Foreign Secretary Philip Hammond.
Downing Street insists that the Government has not given up hope of securing a Commons majority in favour of extending RAF operations against Islamic State from Iraq over the border into Syria.
Mr Hammond said there had been "no change at all" in the stance despite signs that the deployment of Russian aircraft and other developments had reduced appetite for UK involvement.
But he made clear discussions at the Foreign Office with coalition president Khaled Khoja had focused on making a success of a renewed round of peace talks rather than any new military intervention.
He told reporters: "The Russian presence on the ground is a fact now but so too is the Vienna dialogue process.
"We are now talking about how to make sure, when we meet again - next week probably - for the second round of these talks, we can take things forward in a way that means this process becomes real and irreversible."
He said he had "learned a great deal about what is happening on the ground" and "will be able to play a much more useful role in the discussions as a consequence of the exchanges that we have had".
Asked if he would like to see the UK join airstrikes on IS targets in his country, Mr Khoja said: "Any kind of help from our allies in order to get rid of terrorism and get rid of the dictatorship will be welcome.
"We cannot convince the Syrians to support a political process while they are being slaughtered by the regime forces, especially by the air strikes of the regime and of the Russians.
"What we need is to help those moderate fighters on the ground to protect the civilians."
He hit out at Russian claims to be working in partnership with some opposition forces.
"We are not part of the discussions with the Russians. We have declared very clearly that we are facing a Russian occupation in Syria," he said.
"If the Russians would like to help the Syrians, firstly they have to withdraw their forces and allow the Syrians to have their freedoms, their new Syria free of dictatorship."