Set a target of 314 to win, Sri Lanka got home with two balls and four wickets in hand as Charith Asalanka starred with an unbeaten 83 off 72 balls with five fours and four sixes.
The 16-man squad will assemble in Rawalpindi on June 1 for a training camp although English County Championship players Haris Rauf, Hasan Ali, Mohammad Rizwan and Shadab will join later.
Babar Azam and Imam-ul Haq hit steady half centuries before spinner Mohammad Nawaz recorded his best figures as Pakistan beat the West Indies by 120 runs in the second day-night international in Multan.
The 3-0 clean-sweep lifted Pakistan to 90 points, fourth in the 13-team ODI League table while the West Indies are fifth with 80.
Set a tricky 292 to win after a Travis Head 70, the hosts won comfortably with nine balls to spare in Colombo, in their second straight victory in the five-match series.
Shai Hope scored 127 to help West Indies reach 305/8 in 50 overs but with Babar and his boys standing tall, Pakistan reached 306.5 in 42.9 overs to win the first match of the series.
Skipper Rohit Sharma smashed a whirlwind 43-ball 85 in his 100th T20 international as India rode his heroics to register a facile eight-wicket victory over Bangladesh in the second
Pakistan on Saturday recalled all-rounders Iftikhar Ahmed and Mohammad Nawaz for three-match one-day international series against Sri Lanka, starting at Karachi from next week.
Sri Lanka’s depleted national cricket squad left for Pakistan on Tuesday expressing confidence in security promises by the hosts despite reports that the team could be targeted by militants.