The Thomas Jefferson Foundation says:

".....this quotation has not been found in Thomas Jefferson's papers.  It has been suggested that it is a paraphrase of Jefferson's statement in the Declaration of Independence, "...whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government...," although such a paraphrase would seem to be taking some radical liberties with the original version.  The quotation bears a much closer resemblance to Martin Luther King, Jr.'s comment in his famous letter from Birmingham Jail: "One has not only a legal but a moral responsibility to obey just laws. Conversely, one has a moral responsibility to disobey unjust laws."

Regardless, just because you disagree with something doesn't make it unjust.