Guptill hurt his toe after being hit by a Haris Rauf delivery during his side's five-wicket loss to Pakistan here on Tuesday night.
Williamson, who scored 25 runs before being run out, said the Sharjah track was difficult for batting but Pakistan number seven batter Asif Ali timed the ball with ease.
Former captain Mohammad Hafeez hoisted James Neesham for a six as soon as he came out as Pakistan reached 58 for 2 at the halfway mark.
Opener Daryl Mitchell made 27, skipper Kane Williamson contributed 25 while Devon Conway managed to score 27 as the Kiwis struggled to get going against Pakistan's formidable bowling attack.
Pakistan will proceed to take on India in a battle of former champions in their ICC Men's T20 World Cup opener in Dubai on October 24.
Twenty-six players will take part in the camp and throughout the camp, the prevalent COVID-19 SOPs will be observed.