Weigl has been a target for PSG since Tuchel's arrival at the start of 2018-19 after working under the German boss at Bundesliga outfit Dortmund.
The 23-year-old Germany international revealed he considered a PSG transfer in January, but was told to stay by Dortmund.
Tuchel – who is desperate to bolster his squad after PSG won Ligue 1 but fell short in the Champions League – was asked about Weigl at the French Open on Tuesday.
Speaking to Eurosport Germany with Boris Becker, Tuchel said: "Of course [we're interested]. Julian is always an interesting player."
Weigl – who arrived from 1860 Munich in 2015 – made 18 Bundesliga appearances and scored one goal as Dortmund finished runners-up to Bayern Munich.
Dortmund have already lost winger Christian Pulisic to Chelsea, with the deal done in the winter but the American making the move this summer.
The club have also made it clear that highly prized target Jadon Sancho will not be leaving this summer, but could be tempted into selling Weigl as they look to build a Bundesliga title contender again next season.
PSG sensation Kylian Mbappe was also a topic of conversation for Tuchel amid question marks over the World Cup-winning forward.
Mbappe – a reported target for Real Madrid – hinted he could be tempted by a "new project", while Tuchel has refused to offer guarantees over his future.
The 20-year-old scored a Ligue 1-high 33 goals as PSG retained their French top-flight crown, and 39 in all competitions.
He’ll be back in action with the France national team this summer, having won the World Cup in 2018, as they look to secure a spot in the 2020 Euros.
"Kylian has an unshakable confidence in him. I never saw that," Tuchel said. "It could be mistaken for arrogance, but for him, it's total confidence, which is normal when you know he wants to become the best player in the world."