The Home Affairs Select Committee said firms including Facebook, Twitter and Google, which owns YouTube, must show "a greater sense of responsibility".
The three companies have each said they take their role in combating extremism and terrorism very seriously.
Industry body techUK said the MPs had painted "an inaccurate picture" of how much work was being done.
In its report, the committee accuses the companies of "passing the buck" over combating online extremism - although one expert said the conclusions were arguably simplistic and misleading.