Number 10 says it will step in to tell schools not to order primary age children to wear masks.
And Downing Street confirmed at-home testing for pupils will not be made compulsory.
It follows reports that Redbridge Council in East London had written to all 56 of its primary schools advising masks should be worn by pupils as young as four.
"Children in primary schools should not be asked to wear face coverings when they return to school from March 8," the Prime Minister's Official Spokesman said - noting only pupils from year 7 and above will be asked to wear masks.
"The Department for Education are in contact with the local council on that matter."
Number 10 said after the first three tests secondary pupils will take in school, two rapid tests a week will be "made available" to families to take at home.
But they won't be compulsory.
Asked if any checks would be in place to ensure tests were being performed, the PM's spokesman said: "We are making it available to children and to ensure that we can spot cases of the virus early and to ensure that we can get those who are found to be carrying the virus to isolate."
He added: "It's always been the case that testing is a voluntary thing."
The Government has laid out plans for secondary school and college students to be tested twice a week.
But as they return to school they will receive three initial tests at school or college before transitioning to twice weekly home testing.
The Government has confirmed twice-weekly testing for all families and households with primary, secondary school and college-aged children and young people.
Primary school children will not be regularly tested.
Secondary school pupils will have to wear face masks in classrooms when schools reopen to all students on March 8.
The rule will be in place for a "limited period", at least the "initial weeks" following pupils' return to school after more than a month of remote learning at home.
No10 had previously refused to make face coverings mandatory for older children in classrooms despite calls from independent scientists.
Pupils in secondary schools will now have to wear a face covering at their desks, meaning they will be wearing them for most of the day.
Secondary school students already had to wear masks in corridors before England was plunged into its third national lockdown and all schools were shut on January 5.
Under the new rule, the use of face coverings in secondary schools, higher education and further education is being extended to all indoor environments, including classrooms, unless two-metre social distancing can be maintained.
Face coverings are now also recommended in early years and primary schools for staff and adult visitors when social distancing between adults is not possible. Potential scenarios include moving around in corridors and communal areas.
