Sri Lanka reached 222/5 on Thursday when rain stopped play on the second day of the first Test in Rawalpindi, Pakistan's first home Test since a deadly attack in 2009.
Intermittent rain forced an early lunch with just 7.5 overs of play possible in the morning session after Sri Lanka, who resumed at 202/5, adding 20 runs without further loss.
Dhananjaya de Silva was unbeaten on 54, his sixth Test half-century, while Niroshan Dickwella was 15 not out.
The brief period of play saw wicket-keeper Mohammad Rizwan claim a catch to dismiss de Silva off the bowling of 16-year-old pace bowler Naseem Shah, but third umpire Richard Illingworth ruled the ball had bounced before being taken.
Next ball de Silva completed his half-century with two runs off Naseem, who with 2-65 was the pick of Pakistan's bowlers.
The Test is the first in Pakistan since a militant attack on the Sri Lankan team bus killed eight people in March 2009, suspending international cricket in the country as foreign teams refused to visit over security fears.