The attacker blew up his truck outside the base in Mohammad Agha district south of Kabul after being stopped at the gate, officials said.
A local man was killed and many nearby buildings destroyed, they said. At least five policemen were hurt.
Nato denied Taliban claims that many foreign soldiers had been killed.
A Nato spokesman confirmed to the BBC that there had been "a single attack" against Combat Outpost Maclean in Logar province.
He said there had been no Nato fatalities.