Sean Penn is ''attracted'' to Minka Kelly.

The 54-year-old actor, who recently split from Charlize Theron after 18 months of dating, was spotted helping the former 'Friday Night Lights' star celebrate her 35th birthday at one of his favourite restaurants, French Laundry, in Napa, California last month, but they are taking things slowly.

A source close to the Oscar winner said: ''Minka and Sean got along great. But it's unclear where the relationship is going.

''Sean is attracted to her. She's smart and a giving person.''

The duo first met via his Help Haiti Home charity in January 2013 while Minka was still dating actor Chris Evans, 34.

But another source told Star magazine Minka's friends are worried about her dating Sean.

One insider said: ''Sean doesn't exactly have a great track record with women and they're begging Minka to carefully think about taking it any further with him.''

Their rumoured romance comes shortly after it was reported that Charlize had ''abruptly'' ended her relationship with Sean by refusing to return his calls and other messages.

A source previously said: ''As far as I know, Charlize won't talk to him. She just cut if off. They're absolutely done.''

Meanwhile, sources close to the couple have suggested that despite the outward appearance, their relationship was far from perfect.

An insider told US Weekly: ''[It] was very volatile. They both have intense personalities and are control freaks. He's a tough person, and she's no picnic either.''