EBay has removed items listed for sale on its website that claimed to contain small amounts of Hawaiian sand.
The sand, from various parts of Hawaii, ranged in price from $3.50 (£2.60) to $35, the Hawaii-Tribune Herald said.
It is illegal to remove sand, coral, rocks or soil from the shoreline, although sand taken "inadvertently" on clothing or toys is exempt.
Before a revision of the US law in 2013, one gallon of sand per day was allowed to be taken.
"While we haven't been directly contacted by the Hawaii Department of Land and Natural Resources, we are certainly willing to work with them on the best way to address this issue in the future," Ryan Moore, eBay director of global corporate affairs and communication, told the Tribune.
"We've removed the active listings on the marketplace and have educated the sellers that listing these products [is] against eBay policy."
In August 2017, the Mediterranean island of Sardinia also introduced a law banning the removal of sand.
"Taking away a little bottle may not seem a big deal. But if all the millions of tourists did it, tonnes and tonnes would disappear every year," said the island's State Forestry Corp.