More than 2,300 children were separated from their parents after US President Donald Trump's government began a "zero tolerance" policy in early May, seeking to prosecute all adults who crossed the US-Mexico border illegally.
Trump stopped separating children from their parents last month following public outrage and court challenges.
US Homeland Security Secretary Kirstjen Nielsen met with Mexico's foreign minister, Luis Videgaray, and ministers from Central America in Guatemala City to discuss the separations.
"We remain very committed to re-unifying the families that have been separated as a result of illegal entry, and we will work with our colleagues here to repatriate as quickly as possible," Nielsen told reporters.
Videgaray, who repeated his criticism of the policy, calling it "inhumane," made the same pledge. The ministers also vowed to do more to crack down on people smugglers preying on migrants.
Guatemalan authorities said that 11 reunited family groups comprising 131 people were flown back to the country in one of two flights carrying deportees on Tuesday.
A Guatemalan migration official said access to the family groups was restricted. But other deportees still waiting to be reunited with families went to protest their plight outside the hotel where the ministers were meeting in Guatemala City.