It will also soon offer the targets of bullying the ability to restrict interactions with users who are causing them distress.
Instagram has been under pressure to deal with its bullying problem after high profile cases, including the suicide of British teenager Molly Russell.
Instagram said it was using artificial intelligence to recognise when text resembles the kind of posts that are most often reported as inappropriate by users.
In one example, a person types “you are so ugly and stupid”, only to be interrupted with a notice saying: “Are you sure you want to post this? Learn more”. If the user taps “learn more”, a notice informs: “We are asking people to rethink comments that seem similar to others that have been reported.”
The user can ignore the message and post anyway, but Instagram said in early tests that "we have found that it encourages some people to undo their comment and share something less hurtful once they have had a chance to reflect.”
The tool is being rolled out to English-speaking users at first, with plans to eventually make it available globally, Instagram told the BBC.
The company said it will soon roll out an additional tool, called Restrict, designed to help teens filter abusive comments without resorting to blocking others - a blunt move that could have repercussions in the real world.
Once a user has been restricted, their comments will appear only to themselves. Crucially, a restricted person will not know they have been restricted.
Bullying on social media, particularly Instagram, was brought into tragic focus earlier this year.
The father of 14-year-old Molly Russell, who took her own life, said distressing content about depression and suicide on Instagram were partly responsible for his daughter's death.
In April, the British government published its Online Harms white paper, a policy proposal that sought tighter controls on technology firms. It suggests the creation of an independent regulator to direct ways in which firms should deal with all manner of abuse, including bullying.
The paper was met with a mixed response, with some questioning its efficacy, and fears it could be overreaching.
If you've been affected by self-harm, eating disorders or emotional distress, help and support is available via the BBC Action Line.