The first Test between India and Sri Lanka will get underway on March 4 in Mohali.
Both Dickwella and Mendis were handed a 12-month suspension for violating bio-bubble protocols during Sri Lanka's tour of England last year.
Mendis' inclusion for this tour was subject to fitness following a hamstring injury during the fifth T20I against Australia last month. The injury also kept the right-hander out of the recently-concluded T20I series against India.
"Dickwella will be the wicketkeeper, (pacer) Dushmantha Chameera will be rested and will be available for the pink ball Test and Mendis has been ruled out," Karunaratne said in the virtual media interaction on Thursday (March 3).
The Mohali Test marks the Test captaincy debut of Rohit Sharma while it will be Virat Kohli’s 100th appearance in the longest format of the game.
It would also be a landmark game for Karunaratne as he would be leading his country in its 300th Test.
"That's a great feeling...captaining in the country's 300th Test. I did not expect it. It is a great honour for me. I will try my best to give the best result for Sri Lanka," he said.
"I came to know it is Virat's 100th Test. A good decision from the BCCI to allow 50 per cent crowd," he added.
Speaking about the preparations, the Sri Lanka captain said everything has gone as planned when it comes to formulating strategies.
"Sri Lankan players have been training hard and everybody is in good shape. Hopefully they will produce good form in the two Tests," he said.
Dimuth Karunaratne said the team had plans for India’s young batters like Shreyas Iyer and Shubman Gill, who are likely to replace Ajinkya Rahane and Cheteshwar Pujara in the playing XI.
"Yeah, we have a few plans. some youngsters are playing... they are supposed to fill Rahane and Pujara's place. We are trying to execute the plans,” he said.
(With PTI inputs)