Donald Trump just got hit with a lawsuit for the fist fight that went down last week between his security force and a group of Mexican protesters.

Efrain Galicia filed the suit in NYC ... and in it he says his "group of human rights activists of Mexican origin" were attacked by Trump's bodyguards outside Trump Towers last Thursday.

The Trump campaign tells a different story -- saying protesters jumped the guard from behind ... and it's considering filing criminal charges for the incident.

Video of the altercation showed one of the security guards punching a man, believed to be Galicia.

Galicia and 4 others are suing Trump, his campaign, and Keith Schiller ... who is reportedly the guard who threw the punch.