DUBAI, Jan 12 - Iran said on Monday it is keeping communications open with the U.S. as President Donald Trump weighed responses to a violent crackdown on protests that have posed one of the biggest challenges to clerical rule since the 1979 Islamic Revolution.

Trump said on Sunday the U.S. may meet Iranian officials and that he is in contact with the opposition, while piling pressure on the Islamic Republic's leaders, including threatening possible military action in response to violence against protesters.