Liverpool striker Luis Suarez scored an equaliser in the seventh minute of added time in a controversial and dramatic 2-2 draw at Anfield marred by the Uruguay international's bite on Branislav Ivanovic.
Two dropped points meant Chelsea were unable to regain third place from Arsenal, although they still have a game in hand, and are only a point ahead of fifth-placed Tottenham, who have played the same number of games.
"Those three points were very important for us to finish the league third, even more since both Arsenal and Tottenham won, yet we could only get one," Cech wrote on his personal blog.
"Playing in Anfield is always very tough and a game there is very intense. Like yesterday (Sunday), for instance.
"When the match was about to expire, and those minutes of added time were over, we dropped two points.
"It's the most painful way to concede a goal, with no time left to react. The match finished right after that goal.
"Being so close and not winning is really disappointing after more than 96 minutes of good work by the team - and I say 'more' because Liverpool's second goal came in those extra seconds."