Pakistan, Jan. 14 -- US President Donald Trump on Tuesday warned of unspecified "very strong action" if Iran authorities carry out threatened hangings of protesters, amid escalating international concern over Tehran's crackdown. Iranian officials dismissed the warning as a "pretext for military intervention" by Washington.

Read More: Trump urges Iranians to keep protesting, says 'help is on its way'

Rights groups say the demonstrations, sparked by widespread discontent with the clerical leadership, have likely led to thousands of deaths, although verification is difficult due to an ongoing internet blackout. Iranian authorities insist they have restored control after successive nights of mass protests.

Trump, speaking to CBS News, said...