The move follows the interception of a missile fired towards Riyadh on Saturday by Yemen's Houthi rebels who Saudi Arabia says are supported by Iran.
A Saudi-led military coalition will temporarily close all air, land and sea ports to Yemen to stem the flow of arms to Houthi rebels, it said in a statement on Monday carried by the state news agency SPA.
The move, which follows the interception of a missile fired towards Riyadh on Saturday, is likely to further worsen Yemen's humanitarian crisis, which has pushed some seven million to the brink of famine and left more than half a million infected with cholera, according to the United Nations.
"The Coalition Forces Command decided to temporarily close all Yemeni air, sea and land ports," the statement on SPA said, adding that aid workers and humanitarian supplies would continue to be able to access and exit Yemen.
The United Nations and international aid organisations have repeatedly criticised the coalition in the past for blocking aid access, especially to the north, which is held by the Iran-aligned Houthi rebels battling the Saudi-led coalition.
More than 10,000 people have been killed in the conflict, which pits the internationally recognised government, backed by Saudi Arabia and its allies, against the Houthis and forces loyal to former president Ali Abdullah Saleh.
Riyadh says reserves right to respond
Saudi Foreign Minister Adel al Jubeir said on Monday his country reserved the right to respond to Iran's "hostile actions", an apparent reference to the missile fired on Saturday.
Jubeir also said on his Twitter account that Iranian interference in the region harms neighbouring countries and international peace and security.
On Sunday the coalition accused the Houthis of "dangerous escalation (which) came because of Iranian support" after Saudi air defences intercepted the ballistic missile heading towards Riyadh.
The missile was brought down near Riyadh airport without causing any casualties.
Iran rejected the accusation on Monday as "destructive and provocative".
Foreign Ministry spokesman Bahram Qassemi "referred to the war crimes and aggression of the Saudis during the past years and said the reaction by Yemenis is an independent reaction ... and not a move caused by another country's action or incitement", a ministry statement said.
US President Donald Trump also blamed Iran for the attack, but the head of Iran's Revolutionary Guards denied the accusations on Sunday, rejecting them as "slanders".
The Saudi-led coalition has been targeting the Houthis since they seized parts of Yemen in 2015, including the capital Sanaa, forcing President Abdrabbuh Mansour Hadi to flee and seek help from neighbouring Saudi Arabia.
On Sunday a suicide car bomber blew himself up at a security checkpoint in the southern port city of Aden, killing 15 people and wounding at least 20, residents and a security official said.
Aden is the interim headquarters of Yemen's internationally-recognised government.