No;  this sign is not approved for use for several reasons.  The sign may convey to parents and children the message that they are protected if they play in the street when actually there is no such protection;  it may make parents less vigilant if they think a sign protects their children;  and "Warning" signs are supposed to advise of unforseen hazards.  The presence of children in a residential area should not be unexpected.   The recommended treatment is a speed limit.