Theresa May’s deputy told the Commons that British jobs would be at risk if weapons sales to the Saudis stopped because of concerns over war crimes committed during the three-year bombing campaign.
Mr Green was standing in at Prime Minister's Questions yesterday as she flew into the Middle East for a three-day trip to drum up business for trade.
Scottish National Party leader Ian Blackford pressed Mr Green over weapons sales to Saudi Arabia in a heated Commons exchange.
Mr Blackford blasted: "The UK government has received £4.6 billion in selling arms to Saudi Arabia since the war in Yemen began. A war which has created a devastating humanitarian crisis.
"Yemen is now on the brink of famine and Unicef has said that 150,000 children will die by the end of this year.
"Doesn't the First Secretary agree that the best thing the Prime Minister can do with her meetings today is follow the example of the Netherlands and suspend licences for arms sales to Saudi Arabia?"
However Mr Green told MPs it would be a mistake for the government to stop selling weapons to Saudi Arabia, despite a reported 10,000 deaths and millions affected by a cholera epidemic, as it might put jobs at risk.
He also reminded Mr Blackford that the conflict had the backing of the United Nations security council.
Former defence secretary Michael Fallon caused a stir last month when he suggested MPs should stop criticising Saudi Arabia over human rights abuses and possible war crimes as it was hindering the sale of British-made fighter jets.
And anti-war campaigners failed in their High Court bid to bring a judicial review earlier this year pausing arms sales, despite the government being advised by three influential Commons committees to do so pending investigations.
Mr Green claimed that Britain has "one of the most rigorous and robust defence sales regimes in the world" which he said was recognised in a court case last July.
Saudi Arabia is currently on the government's own human rights watch list amid concerns over widespread abuses in the country, including state execution of children and the use of torture.
But continuing the sale of weapons to Riyadh is the right thing to do for Britain's prosperity, according to Mr Green.
The PM is under pressure to raise the issue of child executions by the Saudi state during her visit to discuss post-Brexit trade deals.
Human rights organisation Reprieve said the Prime Minister arrived in Riyadh just after the 125th person had been killed this year.
Reprieve spokeswoman Maya Foya said: "Many more face imminent execution for attending protests calling for greater democratic rights, some when they were only children. They were sentenced to death in courts that relied on confessions gained through torture."
While Ms May's plans to raise the issue of a Saudi-imposed blockade on aid reaching the Yemeni people was welcomed, she was urged to stop selling weapons that contribute to their suffering.
Campaign Against Arms Trade spokesman Andrew Smith said that British weapons have underpinned the Saudi bombardment of Yemen.
He told the Star: "Theresa May is right to raise the issue of the devastating blockade, but the best thing she can do for the people of Yemen is to end the arms sales.
"How many more will die before May and her colleagues finally stop putting arms company profits ahead of Yemeni lives?"
MPs will debate the ongoing crisis in Yemen today in an emergency debate tomorrow after Tory MP Andrew Mitchell warned of a catastrophe of "biblical proportions."
He said current policy will result in a "huge strategic failure" for Saudi Arabia with Britain "dangerously complicit" in the unfolding famine in Yemen.