However,there was"no question of any political censorship,restriction of the freedom of speech or deprivation of the right to stand for elections as alleged by some members of the community,"the government said in a statement.
Activist Joshua Wong tweeted he was among those barred from running for office again.
"A few minutes ago,I was just disqualified from running ... even though I got the highest vote share in the primary with 30,000+ votes obtained."
Rumours of a possible delay to the September elections this week were met with calls for it to be held despite the security law turmoil and the coronavirus pandemic.
US Secretary of State Mike Pompeo and Australian Foreign Minister Marise Payne said in a joint statement on Wednesday that the election should go ahead.
"[They] reiterated their support for the people of Hong Kong to be able to elect Legislative Council representatives via a genuinely free and fair election,which is credible and peaceful,on September 6,"they said.