The two are believed to be alive, the Paris-based group said in a statement.
The kidnappers burst into the house where the two were staying in Nili, in the central Afghan province of Day Kundi, and made off with them in several waiting vehicles around 1 a.m. on Friday (2030GMT Thursday), the statement said. The kidnappers had tied up guards posted outside the house.
The group said it was working to win the workers' release as soon as possible and under the best possible conditions. It said the information it had indicated they were still alive.
Action Against Hunger said it suspended its activities in Afghanistan in response to the kidnapping. The group has been working since 1979 in Afghanistan, where it has 10 foreign staffers and about 150 local employees, according to its Web site.
France's Foreign Ministry confirmed the kidnappings and said a crisis unit would be set up to help win the hostages' liberation.
"Making humanitarian personnel a target is totally unacceptable," the ministry said in a statement. "Humanitarian groups' members are working tirelessly and often in very difficult connotations to help the Afghan people."
Neither statement said who was behind the kidnapping.
Two French aid workers from another humanitarian group, Terre d'Enfance, were kidnapped last year and held for weeks before being released. The Taliban had claimed responsibility for the April 2007 kidnappings and demanded the withdrawal of French troops in Afghanistan.
France currently has about 1,500 troops in Afghanistan, and President Nicolas Sarkozy has pledged to send 700 more soldiers by the end of the year to help NATO-led forces in the country.