The Arab League on Tuesday adopted a resolution calling on Australia and Brazil to "abide by international law" concerning the status of Jerusalem.
It comes after Brazil's president-elect Jair Bolsonaro announced in November his intention to move his country's embassy in Israel from Tel Aviv to Jerusalem.
And on Saturday Australia announced its recognition of west Jerusalem as Israel's capital, although a contentious embassy shift from Tel Aviv will not occur until a peace settlement is achieved
Both Israel and the Palestinians claim Jerusalem as their capital.
The Arab League decided Tuesday to dispatch a "high-ranking delegation" to Brazil and Australia to inform officials there on the need to "abide by international law" concerning Jerusalem.
The decision was taken at an extraordinary meeting at the League's Cairo headquarters attended by delegates from member countries.
The pan-Arab body also called on the UN Security Council to "assume its responsibilities by putting pressure on Israel... and stop its aggression against the Palestinian people".
Israel seized east Jerusalem in the 1967 Six Day war and later annexed it, declaring the entire city its "eternal and indivisible capital", in a move not recognised by most of the international community.
Palestinians claim the eastern part as the capital of a future Palestinian state.
The Palestinian leadership has slammed Australia and Brazil over their plans.
In December the US administration of President Donald Trump decided to move the American embassy from Tel Aviv to Jerusalem and declared the city Israel's capital.
The embassy was transferred in May in a move that sparked outrage in across the Arab and Muslim world.
Most countries have avoided moving their embassies to Jerusalem to avoid hindering peace talks on the city's final status.