Australian Prime Minister Scott Morrison sought on Saturday to postpone an early-August sitting of Parliament, saying the increased community transmissions of the novel coronavirus in the country’s two most-populous states have made it too risky.

Morrison said he had consulted with the parliamentary opposition and had asked the speaker to postpone the two-week session. As the request is largely a formality, lawmakers are expected to meet in the capital Canberra on Aug 24 instead of Aug 4.

“The government cannot...