Some lawmakers and environmental activists had petitioned the High Court of Justice to suspend the export cap, announced in June, arguing in part that it was too generous and more gas should be earmarked for domestic use.
A seven-judge court panel rejected the petitions in a majority vote, removing what had been a significant disincentive to gas investment and development.
Exploration companies had lobbied strongly for a large export quota, saying the Israeli market alone was too small to warrant further investment in developing the fields.
Two of the world's largest offshore fields found in the past decade lie in Israeli waters. Tamar, with an estimated 280 billion cubic meters (bcm), was discovered in 2009, and a year later Leviathan, was found with an estimated 530 bcm.