The League of Social Democrats, Tin Shui Wai Connection and Save Lantau Alliance wanted to march from Victoria Park to the government’s headquarters in Admiralty.
But the police have refused permission for the handover anniversary protest, saying public assemblies and marches are high-risk activities.
“The police have reasons to believe that holding the activities would not just increase the risk of participants and other citizens getting infected, it would also pose grave threats to the lives and health of all citizens, endangering public safety and affecting the rights of others,” the force said in its rejection letter.
The police added that officers had discussed the proposed arrangements for the march with the organisers, but believe that adding certain restrictions “would not help to ensure public order, public safety and protecting other people’s rights and freedoms”.
The three groups said they were appealing against the ban, with a hearing slated to take place on Tuesday evening.
For years, many thousands of Hongkongers took part in July 1 marches to voice their demands on a variety of political issues.
But the police also banned the event last year, citing the pandemic.
The Civil Human Rights Front, which organised the march in the past, did not apply for permission to hold the protest this year.
Some of the front’s most prominent members are in prison over protest or alleged national security offences, and pro-Beijing figures have demanded the group be outlawed.