The Valentine's Day star is said to have been the highest bidder when property mogul Donald Trump offered a one-year membership to his exclusive golf club as part of a fundraising sale in New York in 2008.
The money was to benefit Joe Torre's Safe at Home Foundation, which helps abused women and children.
Lopez failed to pay at the event, and when he was later contacted by Trump National Golf Club executive president Dan Scavino, he promised to send a cheque - but never did, according to the New York Post.
A source tells the publication, "Several attempts by the foundation have been unsuccessful in getting the money. I think Lopez made that bid just to show off in front of the crowd and to impress Donald Trump."
But a spokesperson for Lopez insists there was a misunderstanding over the fee.
The rep says, "George's understanding is that it was paid. George is not a deadbeat. George is very generous."