Williams claimed officers racially profiled her in the incident on 4 July in Maida Vale, west London, which saw the pair being separated from their three-month-old son.
The Metropolitan Police Commissioner Cressida Dick later apologised to Williams.
The inquiry is being carried out by the Independent Office for Police Conduct.
The IOPC said the five officers would be investigated for potential breaches of police standards of professional behaviour relating to use of force; duties and responsibilities; and authority, respect and courtesy.
The Met Police said: "The officers involved are from the Territorial Support Group. No officer is suspended or subject to restricted duties.
"The MPS continues to fully co-operate with the IOPC investigation."
Met Commissioner, Dame Cressida Dick, apologised to the couple a few days after the incident and told MPs that two officers had also spoken to Ms Williams and Mr dos Santos to say sorry for the "distress" caused.