The ban goes into effect on July 4 and will apply to anyone who has been in those four countries within the last 14 days, it said. Saudi citizens returning before Sunday will be exempted.
Saudi citizens and residents returning from these countries will be required to quarantine for 14 days, it added.
Citizens would be banned "from travelling directly or indirectly, without obtaining prior permission from... authorities".
The decision was taken due to "the spread of a new mutated strain of the (Covid-19) virus", it added, without explicitly mentioning the increasingly globally emergent Delta variant.
The variant, first detected in India and now present in at least 85 countries, is the most contagious of any Covid-19 variant yet identified.
The UAE announced last week it had recorded cases of the Delta variant and it has suspended flights to and from India.
Saudi Arabia, meanwhile, has put major limits on the annual hajj pilgrimage. It has officially recorded more than 490,000 cases of coronavirus, including nearly 7,850 deaths.
The oil-rich Gulf state is home to a large expat workforce from Asia, Africa and the Middle East.
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