Haitian Social Affairs Minister Yves Christallin said the police arrested five men and five women with US passports, and two Haitians, as they tried to cross into the Dominican Republic with the children Friday night.
He said two pastors were also involved, one in Haiti and one in Atlanta, Georgia.
"This is an abduction, not an adoption," said Christallin.
Christallin said the US suspects did not have the proper documents to take the children out of Haiti, nor letters of authorisation from their parents. The children were aged two months to 12 years and had come from different places, he said.
"What is important for us in Haiti is that a child needs to have an authorisation from this ministry to leave the country," he said.
US embassy officials were not immediately available Saturday evening to comment on the case.
Haitian officials have voiced fears that child traffickers will take advantage of the chaos after Haiti's massive Jan. 12 quake to slip out of the country with children in illegal adoption schemes.
There is also concern that legitimate adoption agencies may rush to take earthquake orphans out of the country before proper checks have been conducted to confirm that their parents perished.
Haiti's quake severely crippled government agencies and pitched the country into a communications morass.
In an interview with NBC news, a family member of one of those arrested said the Americans were being charged with child trafficking, and that they believed the matter was a misunderstanding over documentation.
The Americans were identified as members of an Idaho-based charity called New Life Children's Refuge, and were being held in a jail cell at the Port-au-Prince judicial police headquarters.
A document posted online by the group asks for donations to bring 100 Haitian children to safety in the Dominican Republic and for volunteers to take care of the children during two-week stints.
Under the heading "Purpose," it reads: "Rescue Haitian orphans abandoned on the streets, makeshift hospitals, or from collapsed orphanages."
It says the group has leased a 45-room hotel in Cabarete as a temporary shelter for the children.
It also includes a prayer request "for God to continue to grant favor with the Dominican government in allowing us to bring as many orphans as we can into the DR."
Christallin said it was "too bad that it was Americans who have been implicated in this affair, because they are helping us (with earthquake relief), as many countries are."
The United States has urged citizens moved by the plight of Haiti's earthquake victims to show patience in adopting children, as reports emerge that some children have fallen prey to human traffickers, or even misidentified as orphans.
Haiti said its prime minister will have to sign off on every minor's departure abroad for the time being.
Keep up with the latest business news from the region with the Emirates Business 24|7 daily newsletter. To subscribe to the newsletter, please click here