The Education Secretary said he wanted to see Covid measures removed in schools "as soon as possible" and said they were in line to go along with restrictions in wider society on July 19.
He was pressed in the Commons on disruption in education caused by the pandemic, which saw 375,000 children out of school last week due to coronavirus outbreaks forcing periods of self-isolation.
The South Staffordshire MP said it was his "top priority" to keep children in schools, and said he understood the "frustration" of parents and children who may feel they are being told to isolate unnecessarily.
He told MPs: "Some restrictions remain in place in schools. What I want to see is these restrictions including bubbles removed as quickly as possible along with wider restrictions in society.
"I do not think it is acceptable that children should face greater restrictions over and above those of wider society, especially since they have given up so much to keep older generations safe over the last 18 months.
"Further steps will be taken to reduce the number of children who have to self-isolate, including looking at the outcomes of a daily contact testing trial as we consider a new model for keeping children in schools and colleges.
"We constantly assess all available data and we expect to be able to confirm plans to lift restrictions and bubbles as part of Step 4. Once that decision has been made we will issue guidance immediately to schools."
Mr Williamson added that he had met the new Health Secretary, Bromsgrove MP Sajid Javid, as well as scientists and public health experts to discuss plans to safely remove restrictions in schools.
He said: "I'm looking carefully every day at how we manage the balance between safeguarding children's education and reducing the transmission of the virus, because I know that there is still too many children having their education disrupted no matter how good remote education is that they are receiving."
Mr Williamson said the Government was expecting the outcome of Public Health England trials involving daily testing in schools in the coming weeks.
A scheme could be implemented from the start of the next academic year, he added, noting that 57 million tests had already been conducted in schools and colleges across the country.
Shadow Education Secretary Kate Green said that with just nine weeks to go until the new term starts, schools still had "no idea" what plans ministers had to keep pupils in class.
She said: "Data published yesterday showed 375,000 children were out of school last week because of coronavirus, it's nine weeks until the new academic year but we have no idea what the Secretary of State plans to keep them in class.
"School leaders dread another last-minute announcement. They need time to put plans in place and their staff also desperately need a break over the summer."
Mr Williamson is understood to favour replacing the bubbles policy – where whole groups of youngsters are sent home if there is a positive Covid case confirmed – with a new, stricter testing regime.
He has pledged to keep school leaders up to date on the plans.
Labour has asked what support will be on offer to schools to support increased testing.