The probe was launched after a man complained to Leicestershire Police that Stella Creasy's children should be taken into care.
The Labour MP told Today on BBC Radio 4 he made the complaint as he disagreed with her campaign against misogyny.
Waltham Forest Council decided no action was needed against her.
The Walthamstow MP told the Today programme the man, from Leicester, had initially emailed her office angry about the work she was doing to tackle violence against women.
She ignored them as she gets "a lot of emails like that, lots of MPs do and you think people are entitled to their opinion".
She then received a call from social services informing her they had held a safeguarding investigation over an allegation her children were at "direct risk".
They then told her they thought she was the person who may be at risk "because of the way in which this person is targeting me", she said, adding social services wanted to know how to raise concerns about her safety with the parliamentary policing system.
"I was horrified and humiliated," she said.
"My children now have a social services record and it sets the green light that in public life, you can target these children. I think most people would think that's unacceptable."
The council said it launched the investigation as it was legally required to following the referral from Leicestershire Police.
A panel, which was made up of social workers, then met to discuss the case.
Although the panel decided no action was needed, it is legally prevented from removing the complaint from its record.
The MP said she was told the complainant would not face criminal sanctions as he was "entitled" to his view her children should be taken into care.
Leicestershire Police said it had investigated a "number of emails" sent to the MP and gave the man a community resolution rather than a formal sanction because the messages did not meet the threshold for a criminal offence.
It said the content of the messages had "understandably caused upset and distress" to the MP and officers had spoken to the sender who admitted he was responsible and apologised.
Ms Creasy said she was not "pushing for a prosecution" but for a caution as that would have meant the details would have gone into the police intelligence database.
"Having worked on harassment legislation myself, the irony is not lost on me that one of the challenges we've been trying to raise in tackling harassment against women, is the attitude of the police and that's exactly what I experienced," she said.
Ms Creasy added she was "passionate about safeguarding" and "we can't have the system corrupted in this way".
The MP also voiced concerns that instances like this were "damaging the whole of public life".
She said MPs did not want to be "put into glass cages" but this was "the reason why a lot of women are put off" standing to be an MP as it is "women who are targeted".
"It's not a matter of free speech, the police acted as if his free speech to argue without any evidence at all - he'd never met me, seen my children, he'd never been in a room with us; he simply disagreed with my views.
"That can't stand in a thriving democracy because it's going to drive people out of it."
The force said it had told the complainant to not contact Ms Creasy and there had been no report of further unwanted contact.
A spokesman said: "Leicestershire Police takes any report of harassment extremely seriously and will carry out a full investigation into the report and take the appropriate action.
"The force remains fully committed to keeping women and girls safe, listening to concerns and tackling violence."
According to the Sentencing Council, a community resolution is an "informal, non-statutory disposal used for dealing with less serious crime and anti-social behaviour where the offender accepts responsibility".
"The views of the victim are taken into account in reaching an informal agreement between the parties which can involve restorative justice techniques," it adds.
Waltham Forest Council said: "All safeguarding allegations are dealt with in line with the national legislation. We have a duty to treat each case seriously and ensure the statutory process is followed."