Sri Lanka are scheduled to play three one-day internationals and three Twenty20 international matches in Pakistan.
The Sri Lankan cricket association (SLC) said on Wednesday it was reassessing the security situation in Pakistan after receiving a warning "of a possible terrorist threat" to its team.
Sri Lanka are scheduled to play three one-day internationals and three Twenty20 international matches in Pakistan between Sept. 27 and Oct. 9 and 10 key Lankan players have already opted out of the series citing security concerns.
SLC, which named weakened ODI and T20I squads for the tour earlier on Wednesday, said in a statement that it had received the warning from the Prime Minister's Office.
"Sri Lanka Cricket today sought the assistance of the Sri Lankan Government to conduct a 'Reassessment' of the security situation in Pakistan ahead of the National Team's planned tour to Pakistan," SLC said.
"The warning highlights that the Prime Minister's Office has received reliable information of a possible terrorist threat on the Sri Lankan team while touring Pakistan.
"Hence, SLC has been advised to take extreme care, and 'reassess' the situation, before embarking on the said tour."
Sri Lanka named Lahiru Thirimanne and Dasun Shanaka its ODI and T20I captains for the tour after incumbents Dimuth Karunaratne and Lasith Malinga decided not to travel.
The other players who chose not to play were Angelo Mathews, Niroshan Dickwella, Kusal Perera, Dhananjaya De Silva, Thisara Perera, Akila Dhananjaya, Suranga Lakmal and Dinesh Chandimal. Kusal Mendis was unavailable for selection due to an injury.
Pakistan are looking to host their first test on home soil — as part of the World Test Championship in December — since a 2009 militant attack on Sri Lanka's team bus in Lahore left six security personnel and two civilians dead while six players were injured.
Pakistan did not host international cricket for six years following the 2009 attack, with the team playing their home matches in the United Arab Emirates, but have hosted teams such as Zimbabwe and West Indies in recent years.
ODI squad: Lahiru Thirimanne (captain), Danushka Gunathilaka, Sadeera Samarawickrama, Avishka Fernando, Oshada Fernando, Shehan Jayasuriya, Dasun Shanaka, Minod Bhanuka, Angelo Perera, Wanindu Hasaranga, Lakshan Sandakan, Nuwan Pradeep, Isuru Udana, Kasun Rajitha, Lahiru Kumara
T20I squad: Dasun Shanaka (captain), Danushka Gunathilaka, Sadeera Samarawickrama, Avishka Fernando, Oshada Fernando, Shehan Jayasuriya, Angelo Perera, Bhanuka Rajapaksa, Minod Bhanuka, Lahiru Madushanka, Wanindu Hasaranga, Lakshan Sandakan, Isuru Udana, Nuwan Pradeep, Kasun Rajitha, Lahiru Kumara.