Foreign Secretary Philip Hammond says Parliament should not be recalled in light of the crisis in Iraq.
Asked about the issue ahead of No 10's emergency committee Cobra, he said: "Not for the moment, no."
Ex-Lib Dem leader Sir Menzies Campbell says it would be in the government's interest to recall Parliament.
He said the humanitarian argument was "overwhelming" - although he was not persuaded that the UK should join US airstrikes in the region.
A cross-party group of MPs has called for Parliament to reconvene as three RAF Tornado jets left the UK to take part in a surveillance mission over Northern Iraq.
The aircraft flew from RAF Marham, in Norfolk, for RAF Akrotiri, in Cyprus, from where they are set to help efforts to deliver aid to refugees trapped on a mountain in northern Iraq.
The Ministry of Defence said RAF cargo planes dropped a further two consignments of aid on Monday night.
US forces have carried out four rounds of air strikes targeting IS militants near Irbil, the capital of Iraqi Kurdistan.
BBC defence correspondent Jonathan Beale said it was "inconceivable" that the RAF Tornadoes would not be armed during flights over Iraq. But he said any prospect of UK planes taking part in strikes "does not seem to be likely at the moment".
Under Commons rules ministers have to ask the Speaker for Parliament to be recalled - and he decides whether to agree. There was a proposal a few years ago to give MPs, rather than the government, the power to demand a recall, but it was never implemented.
The Independent Parliamentary Standards Authority has made explicit provision to reimburse MPs for any expenses incurred in the event of a recall - such as emergency travel to get back to the UK.
The Commons (and Lords) were last recalled on 29 August 2013 to discuss Syria, which was the 27th time since 1948.
Sir Menzies Campbell told BBC Radio 4's The World At One he believed the government "would be well advised" to recall Parliament so it could share what it had done and "at the moment at least" what "it is intending to do".
The arguments for humanitarian intervention were "overwhelming", he said, with reports of "routine brutality" and many people "risking their lives" to flee advancing militants from the Islamic State.
While it was clear ministers had "not ruled out in some circumstances some kind of offensive activity", Sir Menzies said he was not convinced the UK should go beyond helping the US with the provision of intelligence, surveillance and reconnaissance.
"I'm not persuaded at the moment that the UK should join in air strikes along with the US," he said.
"But I think one has to keep an open mind about that because circumstances change very rapidly and if the northern part of Iraq... were to fall, then the consequences of an unstable region would be incalculable."
Referring to past votes on Syria, Iraq and Afghanistan, Sir Menzies conceded that he did not know the mood of MPs.
"But if we were to argue that in this particular case the justification for humanitarian intervention was paramount, then Parliament might be persuaded," he said.
"But it would depend on the case made by ministers, and that's why they should take the opportunity of making their case to the House of Commons so not only they would be better informed about the mood of the House, but Parliament and the country would be better informed."
As Mr Hammond began chairing another meeting of the government's emergency committee Cobra to discuss the next stage of Britain's response to the crisis, MPs took to Twitter to urge a parliamentary recall.
Democratic Unionist MP Nigel Dodds said: "We are calling for the recall of Parliament to discuss crisis in Iraq. We can't sit back when genocide of Christians & minorities continue."
Conservative Conor Burns said: "I have emailed Mr Speaker asking for recall of Parliament to debate UK response to the massacre of Christians and other minorities in Iraq."
Labour's Andrew Gwynne said: "I support an immediate recall of Parliament re the appalling crises in Middle East & Iraq. Recall is in Govt's gift. Come on @David_Cameron!"