(Esteban Felix ~ Associated Press)
Zelaya's supporters clashed with soldiers and police after the government ordered everyone off the streets along the 600-mile border with Nicaragua in a noon-to-dawn curfew.
Wearing his trademark white cowboy hat, Zelaya walked up to a sign reading "Welcome to Honduras" and smiled to cheering supporters at the remote mountain pass surrounded by banana trees.
He stopped a few steps into Honduran territory, however, saying he was negotiating with military officials to let him be reunited with his family in Honduras.
"I've spoken to the colonel, and he told me I could not cross the border," Zelaya said. "I told him I could cross."
Zelaya said he was trying to get in touch with more senior military commanders.
Secretary of State Hillary Rodham Clinton called Zelaya's trip "reckless." International leaders have urged Zelaya not to return to Honduras out of fear it would lead to bloodshed, but Zelaya said he had no choice after U.S.-backed talks with the coup-installed government failed to reinstate him.
That government has insisted it will arrest Zelaya once he returns, ignoring threats of sanctions from nations worldwide if he is not reinstated.
Soldiers formed a human chain near the border crossing but made no immediate move to approach Zelaya as he stood speaking on a mobile phone.
In a statement, the interim government said it still believed in negotiations. Its deputy foreign minister, Marta Alvarado, accused Zelaya of seeking "subversion and a bloodbath."
Zelaya said his reinstatement is necessary to preserve democracy and prevent coups, not only in Honduras but across a region that has seen many in its turbulent political history.
"The people of Latin America and the world have been losing their rights," Zelaya said before crossing.
He appealed to soldiers to lower their weapons when they see him, and asked the interim government of Roberto Micheletti to allow him back.
"Let me return in peace. Let calm return to Honduras," he said.
Thousands of Zelaya's supporters flocked to the border to support his return. The government responded by ordering everyone along the border off the streets from noon until dawn.
But many ignored the order, and Zelaya supporters clashed with security forces that fired tear gas at the crowd. Police reported one demonstrator was slightly injured.
Soldiers set up checkpoints on highways leading to the border area to prevent his backers from massing there. Some made their way on foot after bus drivers refused to risk the trip.
All governments in the Western Hemisphere have condemned the coup, in which soldiers acting on orders from Congress and the Supreme Court arrested Zelaya and flew him into exile. Nations on both sides of the political spectrum say Zelaya's return to power is crucial to the region's stability.
But Washington and the Organization of American States have asked Zelaya to be patient and not return on his own, fearing it could plunge the country into chaos.
"President Zelaya's effort to reach the border is reckless," Clinton said in Washington.
She said it would not help restore democratic and constitutional order in Honduras.
An initial attempt to fly home on July 5 was frustrated when officials blocked the runway of the Honduran capital's airport.
The Honduran military said it would not be responsible for Zelaya's security if he returns, responding to the ousted president's warning that he would blame military chief Gen. Romeo Vasquez "if something happens to me en route to Honduras."
The Defense Ministry suggested Zelaya might stage an assassination attempt on himself to blame Vasquez.
"We cannot be responsible for the security of people who, to foment general violence in the country, are capable of having their own sympathizers attack them," the ministry said in a statement late Thursday.
Honduras' Supreme Court ordered Zelaya's arrest before the coup because he ignored court orders to drop plans for a referendum on whether to form a constitutional assembly. The military decided to send Zelaya into exile instead.
The negotiations stalled after neither side accepted a proposal from Costa Rican President Oscar Arias, the chief mediator. Arias called for Zelaya's reinstatement, amnesty for the coup leaders and early elections.
Associated Press writers contributing to this report included Juan Carlos Llorca in Tegucigalpa, Honduras, and Matthew Lee in Washington.