"I do not want to comment and I want to ignore his comments. All that I am keen as the chief selector is to see Sri Lankan batsmen save the Test," de Mel told AFP.
Sri Lanka are struggling to salvage a draw in the first Test in Brisbane after seeing Australia declare on 551-4 and then getting all out for 211 in their first innings.
The 36-year-old opening batsman on Saturday blamed the selectors for the team's current woes.
"Sri Lanka cricket at this moment of time is not going in the direction it should be going, especially with a set of muppets headed by a joker," Atapattu was quoted as saying on the cricinfo website.
"I don't give credit to the way they have handled selections. If they had handled selections properly we should have a good back-up team.
"For some reasons we don't, and at the age of 37-38 people have to come and play for Sri Lanka when it comes to tough tours like this. If selectors are there only for going on tours and getting perks it is a waste of time."
Atapattu has been lashing out at the selectors since the March-April World Cup in the Caribbean, where he did not play a single match despite being in the squad.
He was also ignored for the one-day series against Pakistan in Abu Dhabi in May and he pulled out of a three-Test home series against Bangladesh in June saying he was not mentally prepared to play Test cricket.
He was not selected in the original squad for the Australian tour, but was brought in as the 17th member following the intervention of the country's sports minister, Gamini Lokuge.
The veteran, who returned to the Test side after nearly two years, scored a gutsy 51 in the first innings in Brisbane and has 16 centuries in Test cricket.