(CNN) Michael Avenatti pitched Michael Cohen on working together against President Donald Trump at their dinner encounter last week, according to a source briefed on the chance meeting.

Cohen, the former personal lawyer to the President, was dining with his son and another person at Scalintella on Manhattan's Upper East Side when Avenatti, the attorney for former adult film star Stormy Daniels, walked into the restaurant. Cohen was eating dessert, according to the source.

Avenatti walked up to Cohen's table and pitched him on working together to resolve their differences, the source said. Avenatti is representing Daniels, whose real name is Stephanie Clifford, in a lawsuit against Trump over a dispute about a nondisclosure agreement that Cohen facilitated.

Cohen has been increasingly distant from Trump since his home, office and hotel room were raided in April as part of a referral to the southern district of New York by special counsel Robert Mueller. Boxes of evidence , as well as several electronic devices, were turned over. The FBI also seized recordings between Cohen and Daniels' former lawyer regarding her nondisclosure agreement.

The source speaking about the dinner meeting said the clear suggestion by Avenatti to Cohen was to work together against Trump.

According to the source, Cohen was stunned and taken aback by Avenatti's proposal. Cohen told Avenatti to speak with his lawyers.

Avenatti told CNN Monday, "that is 100% false. A complete fabrication. Complete bull---. That's completely false."

On Friday, Avenatti told CNN he had a "lengthy" discussion with Cohen that he felt would be an important meeting.

"We had a very open, honest and frank discussion that I found to be extremely productive. It was lengthy. It was frank," Avenatti said.

He added, "Michael and I conversed and I found that meeting to be productive. That meeting could ultimately end up being a critical meeting."

Brent Blakely, one of Cohen's lawyers, declined to get into the details of the encounter at the restaurant.

"Avenatti himself acknowledges having a lengthy and frank discussion with my client, who is represented by me, without my permission. What more is there to say?" Blakely told CNN.

He added that he plans to bring up the issue in court.

"I understand that Mr. Avenatti approached my client at a restaurant last week and attempted to engage him in discussions regarding the litigation," Blakely said. "This is very likely a violation of Rule-2-100, which prohibits counsel from communicating with a represented party. I intend on bringing this matter to the attention of the court on Friday."

Cohen, who once said he would take a bullet for his old boss, signaled earlier this month that he's open to working with federal prosecutors.

Friends of Cohen's told CNN in June that he has signaled that he is "willing to give" investigators information on the President if that's what they are looking for. He has hired two new lawyers-- Guy Petrillo, a former chief of the criminal division of the US attorney's office in Manhattan, and Lanny Davis, who represented President Bill Clinton during the Monica Lewinsky scandal.