Amanda Seyfried and Justin Long
PBG/PA Photos/Abaca; Thelonius/Splash News Online
Is it love for the Lovelace
, 27, has been spotted numerous times this summer with iSteve
actor Justin Long
, 35, most recently Thursday night at Cecconi's
restaurant in West Hollywood, Calif.
"They looked like they were on a dinner date," an onlooker told PEOPLE. "She was in a festive mood."
According to the source, Seyfried – dressed in a black tank and black, wide-brimmed hat – and Long sipped on white wine. "They were both smiling and looked so happy," the onlooker said. "She looked like she was very into him."
Another diner also spotted them.
"They seemed happy and you can tell they are newly dating," says the observer. "They are engaged in the conversation and seem intrigued in what each other has to say. They are very cute."
Seyfried and Long were also seen together at the July 30 Cinema Society premiere of Lovelace
in New York. The two were seen looking "cozy" at the movie's after-party on the Refinery Rooftop lounge, a source tells PEOPLE.
Seyfried, who previously dated Ryan Phillippe
and Dominic Cooper
, admitted to Elle
in its August issue that she had moved on to "someone else" but didn't specify who that someone was.
Long, who will have a recurring role in the new Anna Faris-Allison Janney sitcom Mom
, previously dated Drew Barrymore
Reporting by RAHA LEWIS, DAHVI SHIRA and SYDNEY BERGER