US President Donald Trump has promised to publish all documents on John F. Kennedy's assassination in 1963 to guarantee transparency and end any conspiracy theory on the event.

"After strict consultation with General Kelly, the CIA and other agencies, I will be releasing ALL JFK files other than the names and addresses of any mentioned person who is still living," Trump said on his Twitter account, Efe news reported.

"I am doing this for reasons of full disclosure, transparency and in order to put any and all conspiracy theories to rest."

Trump had on Thursday authorised the National Archives to release 2,891 previously unpublished documents on the historic landmark, but decided to retain some of them because of what official sources described as CIA and FBI pressures.

"I have no choice --today-- but to accept those redactions rather than allow potentially irreversible harm to our Nation's security," Trump said in a memo on Thursday.

However, Trump gave his agencies six months until April 26, 2018, to review the reasons for their decision to keep certain documents hidden and to minimise censored extracts so that they could be published as soon as possible.

He was not satisfied with his agencies' insistence on keeping some materials secret and decided to give them more time to review them with the idea of publishing more documents, although the White House has not given a clear timeline for the next release.