United Nations Secretary-General Kofi Annan said he wished the new administration every success in confronting what he said were enormous challenges facing Iraq.
US President George W. Bush called it "an opportunity for progress".
Arab League Secretary-General Amr Moussa step it was "a step on the right path".
Iraq's parliament approved the government, which includes Shia, Kurd and Sunni party members, headed by new Prime Minister Nouri Maliki, who has vowed to heal sectarian rifts.
Mr Maliki told parliament it was time to "renounce terrorism" and formulate a timetable for the withdrawal of foreign forces.
The new government is the result of five months of wrangling following general elections in December.