"We cannot allow a return to the past. We will not permit it," Mr Chavez said.
"We are here to support, respecting the sovereignty of Honduras."
However, he also threatened military action should the Venezuelan ambassador to Honduras be attacked.
Mr Chavez spoke after talks with Mr Zelaya, President Rafael Correa of Ecuador and Nicaraguan President Daniel Ortega.
Mr Zelaya called his ouster a plot "by a very voracious elite, an elite which wants only to keep this country [Honduras] isolated, in an extreme level of poverty".
Mr Micheletti, who as Speaker of Congress was the next in line to the presidency, told a news conference in Tegucigalpa on Sunday that a nationwide curfew was being imposed for Sunday and Monday, running from 2100 (0300 GMT) to 0600 (1200 GMT) the following morning.
Now we have a new president and will have elections and things will go back to normal
The swearing-in of Roberto Micheletti was greeted with applause in Congress.
In a speech, he said that he had not assumed power under the "ignominy" of a coup d'etat.
The army had complied with the constitution, he said, and he had reached the presidency "as the result of an absolutely legal transition process".
Congress said he would serve until 27 January, when Mr Zelaya's term was due to expire. Presidential elections are planned for 29 November and Mr Micheletti promised these would go ahead.
Both Congress and the courts had opposed Mr Zelaya's referendum, which asked Hondurans to endorse a vote on unspecified constitutional changes alongside the November elections.
But Hondurans say there is a total lack of information about what has happened to their country and their president, our correspondent adds.
Tensions over the issue had been escalating for several days, with the army refusing to help with preparations for the referendum.
Troops arrest Honduran president
Troops stormed the president's residence just before dawn on Sunday. For several hours there was confusion over Mr Zelaya's whereabouts before he turned up in Costa Rica.
He urged Hondurans to resist those who had removed him and flew to Nicaragua late on Sunday.
In Tegucigalpa, Congress said it had voted to remove him because of his "repeated violations of the constitution and the law and disregard of orders and judgments of the institutions".
One man told the BBC that he had been in the city's main square all day, along with 2,000 Zelaya supporters. Jeronimo Pastor described the situation as tense and called on the international community to get involved.
But another resident of the capital said people were relieved at Mr Zelaya's removal. "Now we have a new president and will have elections and things will go back to normal," Kenneth Bustillo told the BBC.
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