Yemenis have denounced Saudi Arabia's decision to close the country's land, air and sea ports, calling it an "unnecessary and dangerous act of collective punishment" that puts millions of civilians at risk and exacerbates the plight of the country's most vulnerable.

The kingdom, which is currently leading a coalition of Sunni Arab states in bombing Yemen, said it was "immediately" closing off access to all of Yemen's ports after Houthi rebels fired a ballistic missile towards the Saudi capital, Riyadh.

Within hours of the missile being intercepted, Saudi Arabia launched a series of air raids on the Yemeni capital, Sanaa, targeting the Houthi-controlled presidential palace, the national security headquarters and the interior ministry.

Yemenis are now being collectively punished for the actions of a few Houthis. Khaled Abdallah, Sanaa resident

In a statement released via the Saudi state news agency SPA, the coalition urged Yemenis and humanitarian groups to "avoid areas of combat operations, areas populated by the Houthis, areas and ports exploited by this Iranian-controlled militia to smuggle weapons, and areas from which this militia launch its attacks against the Kingdom".

"To address vulnerabilities," the coalition said, "... it has been decided to temporarily close all Yemeni ground, air, and sea ports."

Yemen's national airline, Yemenia, which is jointly owned by Saudi Arabia, said it would no longer fly out of Aden and Seiyoun, areas in south Yemen that are under the control of the coalition.

Khaled Abdallah, a 24-year-old resident of Sanaa, told Al Jazeera that Riyadh's latest announcement was nothing short of a "bullying tactic" and would fail to stoke unrest against the Houthis, a group of rebels who control the capital.

"The Saudis want to see us out in the streets protesting against the Houthis. While this may happen over time, they're forgetting they're the ones that have been terrorising us for the last 24 hours, dropping bombs in the darkest hours of the night," Abdallah said.

"The Saudis don't care about Yemenis. They're just playing politics with the lives of the innocent. If they cared, they wouldn't make this unnecessary and dangerous announcement," he added.

"Yemenis are now being collectively punished for the actions of a few Houthis."

'Every Yemeni will suffer'

The closure of Yemen's ports could further limit access for the delivery of humanitarian aid to the Arab world's poorest country, which has been devastated by more than two years of conflict.

Doctors Without Borders, also known by its French initials MSF, told Al Jazeera it was prevented from sending a humanitarian flight from Djibouti to Sanaa on Monday.

"Access for humanitarian flights into Yemen is essential for our medical operations, as well as for other organisations working to support the Yemeni population," Ghassan Abou Chaar, MSF's head of mission in Yemen, said.

"We are continuing to pursue authorisation for flights tomorrow," he added.

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The Saudi-led coalition had previously enforced an air and sea blockade on rebel-held parts of Yemen, only allowing UN-supervised flights and aid shipments, mostly through Aden and the Red Sea port city of Hudaida.

But after a Saudi-led air raid destroyed Hudaida port's industrial cranes in August 2015, shipments have plunged.

According to the World Food Programme, the UN's food-assistance agency, Yemen imported more than 85 percent of its food and medicine by sea before the start of the war.

"Every Yemeni will now suffer," said Habib al-Maqtari, a resident of Houthi-controlled Taiz city.

"The poorest will suffer the most. People who are suffering from chronic diseases and can't get internationally cleared medicines will be the worst hit," he told Al Jazeera.

"And with the currency continuing to collapse, and an absence of basic goods, what is available will spike in price."

Most supermarkets and shops are closed, he said, adding that his weekly shopping that cost 10,000 Yemeni rials ($45) before the war, now costs for 40,000 Yemeni rials ($180).

According to the UN, more than 80 percent of Yemen's 28 million people are in need of some form of emergency aid. Half a million children under the age of five are severely malnourished, and at least 2,135 people have died of cholera in the past six months.

'Riyadh is clutching at straws'

Saudi Arabia and Iran traded barbs over the war in Yemen on Monday as Riyadh said a missile attack "may amount to an act of war" and Tehran accused its rival of war crimes.

"KSA bombs Yemen to smithereens, killing 1,000s of innocents including babies, spreads cholera and famine, but of course blames Iran," Iran's Foreign Minister Mohammad Javad Zarif wrote on Twitter.

Hussain al-Bukhaiti, a pro-Houthi activist based in Sanaa, told Al Jazeera that the blockade would fail to stir unrest against the group and said the kingdom was "clutching at straws" with claims that Iran helped produce the missile that attacked Riyadh.

"The Saudi military campaign in Yemen has been a disaster since day one. They've failed to rally Yemenis against the Houthis, because the people support the Houthis and now they've made up this claim that Iran helped us - it's complete nonsense," Bukhaiti said.

"The only way the Houthis could have received weapons from Iran is through the ports - and all of them are under the control of forces loyal to the coalition - this is a laughable claim."

Bukhaiti denied any Iranian involvement in the war and in the production or manufacture of weapons.

The war in Yemen started in 2014 after Houthi fighters seized control of Sanaa and began pushing south towards the country's third-biggest city, Aden.

Concerned by the rise of the rebels, believed to be backed by Iran, Saudi Arabia and a coalition of Arab states launched an intervention in 2015 in the form of a massive air campaign aimed at reinstalling President Abd-Rabbu Mansour Hadi's government.

Since then, more than 10,000 people have been killed and more than three million displaced, according to the UN.

The coalition has been blamed for several attacks on medical centres, schools, factories and homes.

Follow Al Jazeera's Faisal Edroos on Twitter: @FaisalEdroos