Mathews and his team fell to a three-wicket defeat against the African side in Hambantota on Monday to lose the five-match series 3-2.
Sri Lanka were expected to beat their opponents especially considering that Zimbabwe had not won a bilateral series in eight years.
Mathews said on Monday: “It’s one of the lowest points in my career, and a hard one to swallow.
“Everything went against us, from the toss to misreading the wicket. But there are no excuses. At the end of the day we were not good enough to beat them. They played better cricket.”
There have been suggestions from some that Mathews’ time as national captain has come and gone but he said he would first speak to the selectors.
Under the 30-year-old, Sri Lanka have won a Test series in England and at home against Australia but they have not been up to scratch in ODI cricket since the 2015 World Cup.
The Asian side endured a tough tour to South Africa which ended earlier this year and exited the Champions Trophy in the UK at the group stages.
Mathews continued: “Still haven’t thought about stepping down as captain. There’s time. I’ll give it a bit more thought and talk to the selectors. I haven’t decided anything yet.
“We have not been consistent. The pressure is on all of us. The more we lose, the more pressure we are under. There is no solution for that and the only solution is winning. We try to win games, but we commit too many mistakes.”