The United States, Australia and Canada have also announced a diplomatic boycott of the Games over China's human rights record, a stand that China dismissed as "political posturing".
Coe drew criticism over his comments last week when he said he was "philosophically opposed" to boycotts.
"Boycotts, on balance, are historically illiterate and intellectually dishonest. A political boycott is, frankly, meaningless," Coe told British media on Thursday.
"That's not to be an apologist for countries that do not conform to the basic standards around human rights ... I'm not insouciant or cavalier about human rights. I take them very seriously.
"I don't think over the long haul (boycotts) actually achieve a great deal. There are always unintended consequences. And at the end of the day, the people that most suffer in all that are the athletes."
The Beijing Games begin on Feb. 4.