Dickwella failed a doping test conducted by the Sri Lanka Anti-Doping Agency under World Anti-Doping Agency guidelines during the Lanka Premier League.
"The suspension is effective immediately and will remain in place until further notice," the SLC said in a statement on Friday.
Dickwella captains the Galle Marvels in the Lanka Premier League. He has served as Sri Lanka's wicketkeeper in all formats, last playing for the national team in a test series against New Zealand at Christchurch in March last year.
In June 2021, Dickwella was suspended for a year, alongside Kusal Mendis and Danushka Gunathilaka, for breaching the team's COVID-19 bio-secure bubble during Sri Lanka's tour of England.