Saints grabbed the only try of the game, thanks to a Mark Robinson breakaway score. Fly-half Stephen Myler contributed their other points, while Ian Humphreys and Paul Burke shared the Tigers total.
"We said beforehand that against the teams in that relegation fight it is going to a battle," said Tigers head coach Howard. "Northampton came here to battle and we have to accept that. We said before the game at Worcester last week that all of those games against sides near the bottom of the table would be tight. This was a similar contest."
Tigers were denied a second-half touchdown by the television match official following a rolling maul, but Howard said: "We had some opportunities to score, one with the drive in the far corner and one out wide, but we constructed so little and we will have to have a look at that and work on it. Defensively, we have been doing fine, but our attack was poor.
"It is an opportunity missed. We were poor and I am making no excuses. We have our internationals away but we have got a strong enough squad to win regardless. We have got a big outfit. Between the Munster and Newcastle games we played 28 different players. We should be good enough.
"Now we will have to deal with it during the week and come back better."
Humphreys came off the bench early in the second half but received a knock which meant he limped through the last quarter of the game, though he was able to kick two penalties in that time to keep Tigers in touch and take a bonus point out of a disappointing afternoon.
"I am frustrated and extremely disappointed, and so are the players," said Howard. "We have had very tight games here where we have not played that well and ground out victories but today was particularly poor."