"The leaders of Iran called yesterday (Saturday)," Trump told reporters aboard Air Force One.
A meeting is being planned, the president says, but he adds that "we may have to act before that meeting."
Over 500 people are reported to have been killed in the anti-regime demonstrations in Iran, according to the US-based human rights group Human Rights Activists News Agency (HRANA).
"We're taking this very seriously. The military is looking into it and we're considering some very powerful options. We're going to make a decision," Trump said.
The American leader has previously threatened to "strike very hard" if protesters are killed in Iran.
"It seems like they're starting to do that," Trump said in response to a question aboard the presidential plane about whether Iran had now crossed his red line.
The demonstrations in Iran began in late December when shopkeepers took to the streets to express their dissatisfaction with skyrocketing costs and falling living standards. Since then, other protests have grown massively and now encompass the entire country.
The discontent is rooted in the abysmal economy, with skyrocketing inflation and a currency, the rial, that has collapsed. But like the wave of protests following the death of the young Mahsa Zhina Amini, at the hands of the so-called morality police in 2022, the anger is directed at the regime at large.
