The tax waive will end on August 31.
Government Spokesperson Sansanee Nakphong said that the ministers approved the extension to ease the cost of living, which is set to rise on higher oil prices.
Though the renewed euro zone crisis has weakened oil prices, Dubai crude oil is now near US$100 per barrel.
The diesel excise tax has been cut from over Bt5 per litre to Bt0.0050 for over a year. This helps the government keep the retail diesel price below Bt30 per litre. In Bangkok, the fuel is retailed at Bt29.63 a litre.