A suspected landmine explosion killed a police officer and injured two others on Monday, two weeks after a similar blast in another part of the camp left an officer dead and three people injured.
Another improvised explosive device went off on Tuesday, the Office of the UN High Commissioner for Refugees (UNHCR) said, damaging a police vehicle.
“We are deeply concerned for the well-being and safety of Somali refugees in Dadaab, most of whom are women, children and elderly,” said High Commissioner Guterres.
“For the sake of refugees and those who are there to help them, it is of paramount importance to preserve the peaceful and civilian character of the camps.”
Dadaab is the world’s largest refugee camp, sheltering more than 460,000 people.
Conflict, drought and famine has seen 295,000 people flee Somalia this year, according to the UNHCR — more than half of them ending up at Dadaab.
But since October growing insecurity has crippled the ability of aid agencies to deliver relief.
The organisation said a cholera outbreak at the camp was on the wane however.
“Although new cases are now on a downwards trend, we have nonetheless seen 897 cases since August resulting in three deaths,” it said.
Gunmen seized two Spaniards working for Medecins Sans Frontieres (Doctors Without Borders) from Dadaab in October.
The kidnapping was one of the incidents that spurred Kenya to send troops into Somalia to fight the Al-Qaeda-linked Shebab insurgents who they suspect are behind bombings and shootings targeting security forces.