WASHINGTON, May 28 (Reuters) - The U.S. said on Thursday it has imposed new sanctions on Iran's military oil trade, even as Washington and Tehran reached a tentative agreement to extend their ceasefire and lift restrictions on shipping through the Strait of Hormuz.

The Treasury Department said it had sanctioned eight vessels involved in transporting Iranian crude oil and petroleum products to global markets. The vessels included the Marshall Islands-flagged oil tanker Flora, the Comoros-flagged crude oil tanker Hauncayo and the Panama-flagged tanker Ill Gap.

"We will not allow the Iranian government to increase its oil revenue for the purpose of reconstituting its armed forces and military capabilities," Treasury Secretary Scott Bessent said in a release.

President Donald Trump has yet to approve the deal in the war the U.S. and Israel launched on February 28. The conflict has roiled global markets by closing the vital strait off Iran and Oman, through which 20% of the world's oil and gas normally flowed.

The U.S. also imposed sanctions on more than 15 entities including Worth Seen Energy Limited in Hong Kong, Symphony Shipping and Maritime Management Inc in Dubai, and Mehdiyev Trading Co, also in Hong Kong.