Executors John Branca and John McClain wrote in a letter posted online to fans of the pop superstar that they were doing everything they could to protect his children.
"We are concerned that we do what we can to protect them from undue influences, bullying, greed, and other unfortunate circumstances," states the letter posted just hours after deputies responded for a family disturbance at the hilltop home where Katherine Jackson and her three grandchildren live.
No arrests were made but officials say there is an active battery investigation.
Jackson died in June 2009 at age 50 and left his estate to care for his mother and three children. He left nothing to his father or siblings, who have repeatedly tried to intervene in the estate. Several have expressed doubts about the validity of his will.
Sandra Ribera, an attorney for Katherine Jackson, said authorities were called after the singer's children were accosted by relatives who followed them into their gated community in Calabasas.
"After exiting their vehicles, Jackson family members ran up to Michael's children as they yelled and began to aggressively grab at the cellphones in their hands," Ribera wrote in a statement.
She and sheriff's officials have not identified who was involved in the incident, but video footage appears to show Michael Jackson's siblings Janet, Randy and Jermaine in the driveway of the home.
The video was obtained by Good Morning America and celebrity website TMZ.
Ribera claims "a plan has been in place for the last three years to remove Katherine Jackson from her home and her beloved grandchildren."
Katherine Jackson was reported missing over the weekend but later found to be with her daughter Rebbie and other relatives in Arizona. She has not spoken to her grandchildren – Prince, Paris and Blanket – since leaving the Los Angeles area on July 15.
Sheriff's spokesperson Steve Whitmore said the missing person's investigation into her whereabouts has been closed, as was an inquiry about possible elder abuse of the 82-year-old Jackson family matriarch.
He said deputies interviewed Katherine Jackson after a family business associate warned authorities that she was possibly being emotionally abused by a family member. Whitmore said the elder Jackson emphatically denied the accusations.
He said an abundance of caution has investigators still looking into claims that Katherine Jackson is the subject of financial abuse.
The estate and Katherine Jackson's guardianship of the children are supervised by a probate judge. The judge recently received a financial summary showing that Michael Jackson's estate has earned $475-million in gross profits since his death, and many of his major debts have either been resolved or are no longer delinquent.
The singer died with more than $500-million in debts.
Janet, Jermaine and Randy Jackson were joined by siblings Tito and Rebbie in a letter leaked last week calling on Branca and McClain to resign and accusing them of manipulating their mother. The letter also claims that Jackson's will is invalid.
The estate has denied the accusations and no challenge to the executors has been filed in court.
The estate said it plans to closely monitor the well-being of Katherine Jackson and her grandchildren.
"While we do not have standing to directly intervene, we have monitored the situation and will continue to do so," wrote Branca, a lawyer, and McClain, a music executive. "We believe measures are being put in place that will help protect them from what they are having to deal with." – Sapa-AP