The actor - who plays Colonel Stars and Stripes in 'Kick Ass 2' - embarked on a war of words with pro firearm campaigners after he claimed he couldn't support the superhero sequel's release due to its extreme violence following the 2012 Sandy Hook school shootings.
However, Jim has now withdrawn his personal comments - namely branding his critics "bullies" in an opinion piece for the Huffington Post in April - and said he was "wrong" to insult them, but still stands by his position on gun ownership in the US.
He wrote on Twitter: "Asslt rifle fans, I do not agree wth u, nor do I fear u but I do love u and I'm sorry tht in my outrage I called you names. That was wrong (sic)".
The 51-year-old star added: "Btw. I don't need a crisis mgr, just a conscience. Calling ppl names is inappropriate but my position on assault weapons hasn't changed. (sic)"
Jim announced he would not be promoting 'Kick Ass 2' - which is due to be released in August - in the wake of the Sandy Hook Elementary School massacre in Newtown, Connecticut, last December, in which 20 children and six adults were killed.
He posted on Twitter: "I did Kickass a month b4 Sandy Hook and now in all good conscience I cannot support that level of violence. / My apologies to others [involved] with the film. I am not ashamed of it but recent events have caused a change in my heart. (sic)"
When gun supporters told him to "f**k off and go back to Canada", he bit back, calling them heartless mother**kers unwilling 2 bend 4 the safety of our kids (sic)".