U.S. Secretary of State Marco Rubio upon his arrival at Al Bateen Executive Airport, in Abu Dhabi, United Arab Emirates, Tuesday, June 23. AP-Yonhap

WASHINGTON — U.S. Secretary of State Marco Rubio said Tuesday that no country is allowed to charge tolls on the crucial Strait of Hormuz, calling the channel an "international waterway."

Rubio made the remarks during a press availability in Abu Dhabi, amid concerns that Iran could charge a fee on ships transiting the strait in the future as last week's preliminary peace deal between Washington and Tehran stipulates safe passage of vessels through the waterway "with no charge for 60 days only."

"It's an international waterway. No country is allowed to charge tolls or fees on an international waterway," the secretary said, referring to the Strait of Hormuz.

"That's existing international law. That's the way it is in international waters all over the world."