Ruffalo, 48, has called the second year with no Black nominees "terrible" and has admitted he is considering boycotting the event, reported Us magazine.
Film director Spike Lee, actress Jada Pinkett Smith and her husband Will Smith have already declared their intention to avoid the ceremony.
"I have a lot of sympathy for it (the boycott) and I completely understand why people are protesting. They have to.
"I've been really struggling with it myself because I do a lot with 'Black Lives Matter' and I'm really struggling because I would in essence probably really seriously think about joining them," he said.
"So I totally get it and I support them but I have to demur and I have to stand up for the people I have to stand up for.