Hundreds of thousands of Rohingya have fled Myanmar since August, when the army launched a bloody crackdown in response to attacks on border posts by the armed group, Arakan Rohingya Salvation Army.
Asked at a joint news conference with Japanese Foreign Minister Taro Kono about the rare admission of wrongdoing by the military, known as the Tatmadaw, Suu Kyi said: "The Tatmadaw investigated and will take necessary action on that".
In the past, the military has retaliated against Rohingya villages following such attacks. Over 650,000 Rohingya have since fled across the border to neighbouring Bangladesh.
More than 655,000 Rohingyas have crossed into Bangladesh since August 25 previous year, escaping a military crackdown in the Rakhine state, which many countries and human rights bodies have described as ethnic cleansing. The U.N. and US have described the military operation as "ethnic cleansing" of the Muslim minority, but have not released specific death tolls.
A rescue worker places the body of a Rohingya Muslim boy, who died after their boat capsized in the Bay of Bengal as they were crossing over from Myanmar into Bangladesh, onto a stretcher near Inani beach, in Cox's Bazar district, Bangladesh.
The exact number of the returnees is still unknown, the report said.
Fortify Rights, Amnesty International, and Human Rights Watch described the admission that ethnic Rakhine villagers and security forces killed 10 Royingya Muslims in Inn Dinn village on September 2, 2018 as the "tip of the iceberg", and urged an international investigation.
Ten of the attackers were captured after the security forces drove the rest off by firing into the air, according to the statement.
Angry ethnic Rakhine Buddhist villagers, who had lost relatives in militant attacks, wanted to kill the captives, and stabbed them after forcing them into a grave on the outskirts of the village. Then members of the security forces shot them dead, the military said.
"We have chose to provide the aid in response to the agreement between Myanmar and Bangladesh to represent an worldwide message of support so that the repatriation can be carried out promptly", said Japanese Foreign Ministry official Shinobu Yamaguchi.
The army chief's office said "action" would be taken against villagers and security members involved in the violence at Inn Din.
James Gomez, Amnesty International's Southeast Asia and Pacific director, said the acknowledgement marked "a sharp departure from the army's policy of blanket denial of any wrongdoing".
The Independent Permanent Human Rights Commission of the Organisation of Islamic Cooperation said the admission substantiated allegations made by human rights groups and the United Nations of ethnic cleansing against "the most persecuted Rohingya people".