The siege began at the weekend when Jewish settlers closed off the road to the three homes in the Palestinian village of Qusra and set up a tent in their front yards, refusing to allow anyone to enter or leave.
The settlers had earlier cut off their electricity and water.
By Thursday evening, Israeli troops were still holding positions in three Qusra homes, according to Mayor Abed Al Athem Wadi and to residents: one on the village outskirts, among the three that are besieged by settlers; and two closer to the village heart.
Reuters photos showed several Israeli soldiers standing outside one of the homes.
The soldiers informed the families that operations in Qusra may last until Sunday, village residents said.
In a statement, the military said that soldiers had been deployed in Qusra since Thursday morning to protect residents and maintain security, and "were instructed that the Qusra residents will remain in their homes".
The military added that "soldiers will not operate inside the Palestinian family's home located near the site where the tent that was evacuated and dismantled had been erected".
It was not immediately clear which of the three homes the military was referring to.
Loui Ridi, a Palestinian-US citizen based in Ohio whose brother is besieged in his home, said that he felt helpless.
"It is terrifying, frustration, fear of my family for their lives," he told Reuters in a phone interview.
Ridi said he had been watching the developments over the security camera installed in his Qusra home but that the soldiers removed it during the day.
He was planning to travel to the home soon, he said.
The United Nations said in a statement that 15 Palestinians including two children were trapped inside their homes with no water or electricity.
The military has come under increasing pressure to halt rogue land seizures by settlers emboldened by the religious-nationalist government of Prime Minister Benjamin Netanyahu, which has spearheaded a rapid expansion of settlements in the West Bank.
Earlier on Thursday, a day after troops deployed tear gas in a failed attempt to remove the settlers, it said it had sent more troops to the area "to carry out defensive missions and patrols in the area to maintain security and protect the area".
Video from earlier in the week showed several Israeli men in green military garb joining the settlers in a morning prayer in the tent.
The military said it was taking disciplinary action against any personnel involved.
The two families under siege in the area say they are running low on supplies and that the settlers have been damaging their property, throwing stones at their homes and shouting insulting language at them.
The US ambassador to Israel Mike Huckabee said the Israeli military and police "have gone at our request to remove the Israeli terrorists doing this," adding: "The actions of those doing this to this family's home is criminal."
Ridi welcomed Huckabee's remarks but said they were not enough.
"We need protection. We need supplies. We need to live freely in our house."
The West Bank, territory Israel captured in the 1967 Middle East war, is home to three million Palestinians and 500,000 settlers.
There are 146 settlements in the West Bank, as well as 390 smaller outposts, according to the Israeli settlement watchdog group Peace Now.
with AP
