While Smith denied any bad intent, he was fined $25,000 after using "hostile and inappropriate language" during a Twitter exchange with Jennings, who originally made a belittling comment regarding Smith's younger brother, Chris.
Chris Smith was sent down to New York's Development League affiliate Monday after failing to get into any of the first nine games.
The Knicks have had a rough go of it, dropping six of eight since beating Milwaukee in their season opener. Smith, who averaged a career-best 18.1 points last season, has posted just 9.8 on 22.6 percent shooting in four games since returning from suspension.
New York (3-6) is allowing 99.7 points per contest after giving up 95.7 last season.
"We keep digging ourselves deeper and deeper - I know it's early in the season, you've got to take it day by day - but at the rate this is going, we're going to be in too deep of a hole to dig out," forward Carmelo Anthony said.
"It ain't got nothing to do with making shots or missing shots. We're just not doing it on the other end. We're not defending, we're not giving no effort. We're not playing right now."
New York is hoping to avoid a third straight loss after falling 110-90 to Atlanta on Saturday. Anthony had 23 points and 12 rebounds as the Knicks allowed the Hawks to shoot 56.4 percent.
"I think everything that we're doing is correctable, but I think effort has got to come behind it a little bit more and we've got to be true to ourselves, because we're not playing well as a unit right now," coach Mike Woodson said.
"We've got to figure out who we are. ... That's the only shot I think we're going to have in terms of getting back in the winner's circle consistently."
If their recent efforts against the Pistons (3-6) are any indication, the Knicks may be able to bounce back. New York has taken 11 of 12 from Detroit, including seven straight by an average of 18.8 points.
Anthony is averaging 27.3 points on 51.9 percent shooting in his last three matchups against the Pistons, while Smith is averaging 18.7 during a six-game stretch.
Losers in five of six, the Pistons return home following Sunday's 114-99 defeat to the Lakers. Jennings had 23 points and 14 assists but Detroit had no answer for Los Angeles, which shot 52.2 percent.
"They started making shots, and that's the nature of the beast," said forward Josh Smith, who had 18 points. "Offense comes and goes, but defensively I think we should have stayed in tune to our philosophies. That's where we let the game slip away ... on the defensive end."
The Pistons are surrendering 103.8 points per game and rank last in the league with an opponent field-goal percentage of 48.9.
Aside from trying to contain Anthony, Detroit will need to keep a close eye on Andrea Bargnani, who is averaging 20.2 points in the last five games. He compiled 23.4 in his last seven against the Pistons while with Toronto.
Jennings averaged 20.0 points in 14 meetings against New York while with Milwaukee, his second-highest mark versus any Eastern Conference team. He leads the Pistons with 18.3 points and 7.3 assists per game.