The former Liberal Democrat deputy prime minister, now Facebook’s head of global affairs, said social media platforms have a “profound responsibility” to safeguard teenagers.
Speaking in an interview with the BBC, he also admitted the way the firm pays tax is “unsustainable”.
Molly Russell, 14, took her own life in 2017 and her father Ian Russell has recently said Instagram, which is owned by Facebook, “helped kill my daughter”.
The teenager viewed images on the site which appeared to promote self-harm.
Sir Nick said: “We’re going to look at this from top to bottom and change everything we’re doing if necessary to get this right.”
He said Facebook will work with charities including the Samaritans, adding: “They do say that in some instances it’s better to keep some of the content, some of these distressing images up, if that helps people make a sort of cry for help and get the support they need.”
But Sir Nick said there was a “line” between which content should be kept and which should be removed.
“The race is really on to make sure that Molly’s dad feels that the responsibility which is incumbent on Instagram and Facebook is now being properly taken up, and one of the things in this new role that I hope to do is to accelerate that process.”
Referring to the way global technology firms pay tax, Sir Nick said policy “needs to change”.
“I think the tax arrangements for Facebook globally and indeed for the digital sector as a whole are unsustainable,” he said.
He said Facebook pays more than 4 billion dollars (£3 billion) in taxes annually but the way it is paid is “unbalanced”.
“The vast bulk of that tax is paid in the United States, not in the United Kingdom or France and Germany,” Sir Nick said.
“That is the thing that is unbalanced. Of course it’s unbalanced to have an American company, yes that’s where the value is created, catering to the world yet paying the vast majority of tax only in one country, one jurisdiction.”
Sir Nick also said governments have a place in regulating social media.
He added: “I think it’s perfectly legitimate for governments to say, ‘look, we want to take our responsibility as governments or legislators to set boundaries’.
“I don’t think it is sustainable for tech companies to just say no we don’t like all regulation.”