"Without political will, we will see more coups such as the one that toppled Manuel Zelaya in Honduras," he said.
Zelaya has been holed up in Brazil's embassy in Honduras since Monday. He had been in overseas exile since July, when he was forced from the country at gunpoint, but made a surprise return to Honduras on Monday.
Brazil has warned Honduran security forces not to enter the embassy in the capital, Tegucigalpa, and is seeking an urgent meeting of the UN Security Council to address the crisis.
Rumors of killings, bullet-injuries and arrests following rioting have been emerging from Tegucigalpa, which remains under curfew.
"The international community demands that Mr Zelaya immediately return to the presidency of his country and must be alert to ensure the inviolability of Brazil's diplomatic mission in the capital of Honduras," Lula told the UN General Assembly in New York.
Venezuelan President Hugo Chavez also called for international action, telling reporters: "The United Nations should demand that Zelaya be reinstated to government again."
Chilean president Michelle Bachelet in her UN address also called for the immediate compliance of the San Jose Agreement which demands the reinstatement of Zelaya, and a similar position was expressed by Uruguayan leader Tabare Vazquez,
In Honduras, troops have surrounded the embassy. Electricity, water and telephone services were cut off for a time on Tuesday before being partially restored.
The de facto leader of Honduras, Roberto Micheletti, says he is willing to talk to Mr Zelaya. But Mr Micheletti said Mr Zelaya must first accept that planned presidential elections would be held in November.
However UN Secretary General Ban Ki-moon said that "conditions needed to organize the November election have not been met" and therefore the UN is withdrawing its support for the electoral event to Honduras Electoral Tribunal.
The interim government said on Wednesday that the political crisis has led to losses of millions of dollars. Mr Micheletti has urged Brazilian officials to either grant Mr Zelaya political asylum or hand him over to Honduran authorities.
A curfew in the capital, in force since Monday afternoon, has been extended until 6 pm local time on Wednesday evening.
On Wednesday morning, the capital's deserted streets became crowded with people trying to buy food, water and other supplies.
Organization of American States Secretary General José Miguel Insulza said he would go to Honduras when the airports re-open and "if there is a meaningful contribution that we can make."
The political crisis erupted after Mr Zelaya tried to hold a non-binding public consultation to ask people whether they supported moves to change the constitution.
His opponents said the move was unconstitutional and was aimed at removing the current one-term limit on serving as president, so paving the way for Mr Zelaya's possible re-election.
Mr Zelaya has denied this and said he always intended to hand over to his elected successor in January.
Mercopress