International Development Secretary Justine Greening has insisted airdropping aid to besieged Syrian towns would be a "last resort" after the United Nations urged Britain and allies to consider the idea.
Ms Greening said there were significant difficulties with the tactic - including the risk that the supplies would end up in the hands of the forces laying the siege.
The comments came ahead of a crucial international summit in London next month on the response to the Syria crisis, where Britain is aiming to secure funding pledges, and action to boost economic opportunities for refugees in the region.
David Cameron is due to push the agenda at the World Economic Forum in Davos over the coming days. On Friday he will jointly host an event with Queen Rania of Jordan encouraging business and political leaders to take "practical steps" to create jobs in countries that have taken in large numbers displaced by the raging civil war.
Ms Greening, who visited the region last week, said the average length of time people remained a refugee was now 17 years, and the London conference had to address "long term issues of jobs and education".
Many communities in countries like Jordan were struggling to cope with sharp population increases, and needed help with issues such as economic infrastructure, schools and refuse systems.
Proposals on the table include allowing more Syrians to run businesses in refugee camps and trade with host communities, and generating investment at preferential rates by institutions such as the World Bank.
Ms Greening told a briefing for journalists that the summit on February 4 - co-hosted by the UK, Norway, Germany, Kuwait and the UN - would seek pledges of aid funding for the next two to three years - rather than for a single year as was usually the case.
She was asked about a letter from UN under-secretary general for humanitarian affairs Stephen O'Brien, in which he argued that "all options need to be in the table" in relation to airdrops for besieged towns facing starvation.
Mr O'Brien suggested the UK and US military could carry out airdrops without following UN guidelines, which state that permission has to be obtained from Bashar Assad's government.
"Given the appalling level of need in Syria and our collective responsibility to act, I believe we have reached a moment where all options need to be on the table," he wrote.
Ms Greening said the UK was "working with the UN generally to make sure we try and access some of these harder to reach and besieged areas".
Pointing out that Madaya, which recently faced a crisis, was only a short distance from the capital Damascus, she said: "They (airdrops) would really be something that would be a last resort because they are something that is less effective in getting aid to people, and of course often less safe. In the end what we need to do is actually frankly have the actors on the ground."
Ms Greening added: "We are not ruling anything out, but the key is making sure that we can actually achieve what we are trying to do.
"Some of the difficulties of dropping from air are clearly you have to do it from height to be safe, that then creates real challenges on being able to target effectively.
"Obviously you do not want to drop from significant height aid to areas where it can drop in the wrong place and be helping to feed and support the very people who are helping to besiege town.
"It is a significant operation... There is no getting away from the fact that we should be seeing international humanitarian law adhered to and we continue to see making sure that regime complies with it as one of the key things we need to see progress with."
Labour backbencher Jo Cox said: "The UN has asked the Government to put 'all options on the table' to help starving Syrians, and this should include contingency planning for UK airdrops.
"The priority has to remain securing a lasting ceasefire and political transition but as the humanitarian crisis in Syria worsens and Assad continues to refuse ongoing access to many besieged communities airdrops should not be ruled out."