Read More, July 20 -- US seeks Hormuz reopening pledge from Iran

Speaking before departing for the ASEAN summit in the Philippines, Rubio said the United States was prepared to continue diplomatic efforts with Tehran but stressed that negotiations must be based on real commitments and compliance.

"If Iran is violating the terms of any understanding, then that agreement cannot remain effective," Rubio said, adding that Washington had made several attempts to engage with Iran and would continue pursuing diplomatic options.

The US secretary of state claimed that Iran was using the strategic waterway as leverage amid ongoing tensions in the region. He said Washington would continue taking necessary measures to protect international shippin...