Honduras' new leaders defied growing global pressure on Monday to reverse a military coup, arguing that they had followed their constitution in removing a leftist president who attacked it.

Presidents from around Latin America were gathering in Nicaragua for meetings Monday on how to reverse the first coup in Central America in at least 16 years.

The Obama administration and European governments denounced the coup. U.S. officials said they were working for the return of ousted President Manuel Zelaya and European officials offered to mediate talks between the two sides.

But Venezuelan President Hugo Chavez took center stage in the region as he defended his ally Zelaya by casting the dispute as a rebellion by the region's poor.

"If the oligarchies break the rules of the game as they have done, the people have the right to resistance and combat, and we are with them," Chavez said in the Nicaraguan capital, Managua.

He threatened to "overthrow" the new leader sworn in by lawmakers, Congressional President Roberto Micheletti — who replied in an interview with HRN radio on Monday: "Nobody scares us."

Zelaya was seized by soldiers and hustled aboard a plane to Costa Rica early Sunday, just hours before a rogue referendum he had called in defiance of the courts and Congress, and which his opponents said was an attempt to remain in power after his term ends Jan. 27.

Micheletti said he would only serve out the end of Zelaya's term, which ends in January following presidential elections set for November.

"We respect everybody and we only ask that they respect us and leave us in peace because the country is headed toward free and transparent general elections in November," Micheletti said.

His designated foreign minister, Enrique Ortez Colindres told HRN on Monday that no coup had occurred. He said the military had merely upheld the constitution "that the earlier government wanted to reform without any basis and in an illegal way."

Troops with riot shields surrounded the presidential palace on Monday and armored military vehicles were parked in front.

But soldiers made no attempt to clear away about 200 pro-Zelaya protesters who were burning tires and other debris, as well as blocking streets with downed trees and billboards.

"We want out elected and democratic president, not this other one that the world doesn't recognize," said Marco Gallo, a 50-year-old retired teacher, who said he was on his way to join the protests in front of the palace.

The Honduran constitution limits presidents to a single 4-year term and forbids any modification of that limit. Zelaya's opponents feared he would use the referendum results to try to run again, just as Chavez reformed his country's constitution to be able to seek re-election repeatedly.

Micheletti said Sunday that the army acted on orders from the courts, and the ouster was carried out "to defend respect for the law and the principles of democracy." But he threatened to jail Zelaya and put him on trial if he returned.

Micheletti also hit back at Chavez, saying "nobody, not Barack Obama and much less Hugo Chavez, has any right to threaten this country."

Earlier, Obama said in a statement he was "deeply concerned" about the events, and U.S. Secretary of State Hillary Clinton said Zelaya's arrest should be condemned.

"I call on all political and social actors in Honduras to respect democratic norms, the rule of law and the tenets of the Inter-American Democratic Charter," Obama's statement read.

For those conditions to be met, Zelaya must be returned to power, U.S. officials said.

Two senior Obama administration officials told reporters that U.S. diplomats were working to ensure Zelaya's safe return.

The officials said the Obama administration in recent days had warned Honduran power players, including the armed forces, that the U.S. would not support a coup, but Honduran military leaders stopped taking their calls.

The president of Latin America's largest nation, Brazil's Luiz Inacio Lula da Silva, said on his weekly radio program Monday that his nation will not recognize any Honduran government that doesn't have Zelaya as president "because he was directly elected by the vote, complying with the rules of democracy."

He also said Honduras risks isolation from the rest of the hemisphere.

"We in Latin America can no longer accept someone trying to resolve his problem through the means of a coup," Silva said.

In Brussels, the EU's External Relations Commissioner Benita Ferrero-Waldner urged "all parties involved to resolve their differences peacefully." She said the EU's executive Commission "stands ready" to help start the talks.

Officials said EU envoys were meeting their Central American counterparts in Brussels Monday to discuss the coup and what implications it could have on free trade negotiations between the EU and Honduras, Guatemala, El Salvador, Nicaragua, Costa Rica and Panama.

Zelaya said soldiers seized him in his pajamas at gunpoint in what he called a "coup" and a "kidnapping."

"I want to return to my country. I am president of Honduras," Zelaya said Sunday before traveling to Managua on one of Chavez's planes for regional meetings of Central American leaders and Chavez's leftist alliance of nations, known as ALBA.

Some of Zelaya's Cabinet members were detained by soldiers or police following his ouster. And the rights group Freedom of Expression said leftist legislator Cesar Ham had died in a shootout with soldiers trying to detain him. A Honduran Security Department spokesman said he had no information on Ham.

Sunday afternoon, Congress voted to accept what it said was Zelaya's letter of resignation, with even the president's former allies turning against him. Micheletti, who as leader of Congress is in line to fill any vacancy in the presidency, was sworn in to serve until Zelaya's term ends.

Micheletti belongs to Zelaya's Liberal Party, but opposed the president in the referendum.

Micheletti acknowledged that he had not spoken to any Latin American heads of state, but said, "I'm sure that 80 to 90 percent of the Honduran population is happy with what happened today."

The Organization of American States approved a resolution Sunday demanding "the immediate, safe and unconditional return of the constitutional president, Manuel Zelaya."

U.N. Secretary-General Ban Ki-moon condemned the coup and "urges the reinstatement of the democratically elected representatives of the country," said his spokeswoman, Michele Montas.

The Rio Group, which comprises 23 nations from the hemisphere, issued a statement condemning "the coup d'etat" and calling for Zelaya's "immediate and unconditional restoration to his duties."

And Taiwanese President Ma Ying-jeou canceled a planned visit to Honduras, one of just 23 countries that still recognize the self-governing island.

Coups were common in Central America until the 1980s, but Sunday's ouster was the first military power grab in Latin America since a brief, failed 2002 coup against Chavez.

It was the first military ouster of a Central American president since 1993, when Guatemalan military officials refused to accept President Jorge Serrano's attempt to seize absolute power and removed him.