India, Sept. 6 -- Iran's parliament speaker warned on Sunday that any future American attack on the country would be met with a "faster, heavier and more painful response," a day after US forces struck three Iranian oil tankers in the latest escalation of the months-long conflict between Washington and Tehran.

"The rules of the game have changed, and from now on, any transgression against the interests and security of Iran will receive a 'faster, heavier, and more painful' response," Mohammad Bagher Ghalibaf said in a speech published on his Telegram channel.

Iran-US War Latest Update: What triggered the latest exchange of attacks?

The US Central Command (CENTCOM) said American forces struck the tankers after Iran fired ballistic missi...