Rioting acceptable? Not according to the 1st Amendment of the US Constitution:
Amendment I
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
Of course, liberal dems have a weird idea of what the word 'peacefully' means, or the question would be even be asked in the first place.
All those libbies carrying Mexican flags, now need to now rush out a get Iranian flags to display in protest : )