The Maldives was to be the final stop in the monarch's ongoing Asian tour that has already taken him to Malaysia, Indonesia, China and Japan.
Foreign Minister Mohamed Asim said a new date for King Salman's trip to the Indian Ocean archipelago would be announced later.
Dozens of people tested positive this month for the H1N1 influenza strain, also known as swine flu, Maldivian health authorities said. Two people have died so far.
The government has ordered the closure of schools in the one-square-mile (2.5-square-kilometer) capital island of Male to prevent the spread of the disease and has discouraged residents in neighboring islets from visiting.
The country's main opposition, the Maldivian Democratic Party (MDP), had protested the planned state visit, accusing President Abdulla Yameen of planning to sell an atoll to Saudi investors, a charge the government has denied, AFP reported.
"With growing public outrage and strong opposition to President Yameen's attempts to sell-off Faafu atoll to the Saudi royal family, the MDP feels that the time is not right for the royal visit," the party said in a statement.
Yameen lifted a ban on foreign ownership of real estate in 2015.
Land is scarce in the Maldives where 99.9 percent of its territory is sea and the nation's 1,192 tiny coral islands account for just 300 square kilometers (115 square miles) of land.
However, the islands are strategically located -- scattered some 800 kilometers (500 miles) across the equator -- straddling the main East-West international shipping lanes.
The country is a popular upmarket holiday destination but its image has been hit by political unrest in recent years.
Opposition leader and former president Mohamed Nasheed is currently living in exile in London after he was jailed on terror-related charges widely criticized as politically motivated.