The FA has said violent incidents targeting match officials at football games remain "few and far between" after fears were raised by a league chairman.
Graham Ekins, chairman of Surrey Youth League, wrote to clubs to warn against a rising pattern of abusive behaviour at matches.
On one weekend of matches in the county, a parent threatened to stab a referee, another headbutted a volunteer linesman and young players threatened to vandalise a changing room.
But the FA said its Respect campaign has resulted in a "significant drop" in dissent towards referees and more extreme incidents are very rare.
A spokesman said: "Incidents of dissent are never pleasant - and the notion that they are in any way part and parcel of the game is one that the Respect programme was established to dispel.
"With a significant drop in the occurrence of this type of caution over the life of the programme, it is clearly working.
"More extreme incidents such as referee assaults thankfully remain few and far between. Across an estimated 1.2 million games last season, the number of reported incidents amounted to a tiny fraction of 1% - which puts the scale of the problem into context.
"However there is no room for complacency. The FA remains vigilant and takes the view that one serious assault is one too many."
In an open letter on his league's website, Mr Ekins said he feared for the lives of match officials, citing the death of a linesman at a junior match in the Netherlands in 2013.
He said: "Would you want your name associated with a children's competition that resulted in the death of someone as a consequence of violence?
"Don't believe it wouldn't happen. It did to a linesman at a children's match in the Netherlands three or four years ago. If this continues I fear that this may be the result here.
"This cannot continue. You as clubs and and all people involved in trying to voluntarily run children's football need to take back control from thugs and idiots that are doing a great job of spoiling Sunday mornings for children and then occupying league officers' time for the rest of the week while we clear the mess up."
He added that clubs and individuals who commit violence should be "ashamed" and suggested the league could withdraw all referees if the problem persisted.
A Surrey County FA spokesman said: "We are aware of the recent press coverage arising from last weekend's football matches, we have begun to investigate the incidents through our Raising Standards Working Group which works closely with youth leagues to ensure allegations of this nature are thoroughly investigated and charged under FA regulations."
Surrey Youth League runs competitions for children aged from six up to under 18. Referees are paid between £15 and £30 per match.