The government last month tabled a draft bill to raise about 700 million euros from new gaming licences and royalties this year, as part of its EU/IMF bailout.
But ruling Socialist party MPs said the law might lead to gaming excesses.
"We should not go towards full deregulation of gaming and gambling," PASOK MP Dimitris Papoutsis told Reuters after Finance Minister George Papaconstantinou presented the draft legislation to members of his party.
Papaconstantinou told lawmakers he would retract the law for further consultation, another Socialist MP present at the meeting told Reuters.
"There were objections that Greece would become a vast casino," the MP said.