Lewis was taking charge of Oxford for the first time since Chris Wilder departed for Northampton earlier this week and maintained the U's unbeaten away record, although they were made to work for it by an impressive Exeter side.
"I think it is a point gained, these are one of the better teams in the league although I know their league position doesn't show that at the moment," Lewis said.
"They played some good football and kept possession well. I thought we closed the ball down at the right time and put them under pressure. With a bit more quality at times we could have possibly opened them up. We got into positions that didn't quite come off for us.
"They could have nicked it at the end. We had a couple of breakaways where we could have nicked it. But Ryan Clarke has produced two great saves.
"It is trying to get the balance of winning the game and making sure you don't lose it. We want to be positive and win games which we have done all year away from home.
"But it is a tough place to come to but in the last four games we have won two and drawn two which is a good run in anyone's book. We showed some great spirit and I am really pleased for the boys."
Exeter were the better team throughout, but their latest blank is their fifth in the last six league games at St James' Park.
They did come close when Arron Davies' dipping volley was tipped onto the bar by man of the match Ryan Clarke, the Oxford goalkeeper.
"I was very pleased with the team's effort and commitment, we looked a proper team out there," Tisdale said.
"Despite the results of late, they showed no signs of wilting and I am delighted to have kept a clean sheet as well as it is something we have not had for a long time.
"We worked very hard for it and it was good to see one of our teams at the end of a game doing the pushing and trying to win it and doing it well. We came very close to a winner.
"I am very pleased with a point and very pleased with the performance. I'm very pleased with the commitment and it was a real team effort, so I am very pleased.
"Oxford didn't have many chances and that is about an all-round performance. You can curse luck when there is a deflection, but we worked hard to stop the ball from coming into the box and giving the opposition opportunities."
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- Ryan Clarke